Standards For Efficiency Calibration Research Articles

Accelerator production and nuclear aspects of 88Y: An efficient radiotracer

Yttrium-88 (T1/2 = 106.6 d, Ib+ = 0.2% and IEC = 99.8%) is used in mixed gamma efficiency calibration standards and also as a substitute for 90Y to quantify the biodistribution of Y-pharmaceuticals in animals. Yttrium-88 and strontium-85 as gamma emitting radiotracers were produced via natSrCO3(p, xn) and natRbCl(p, xn) nuclear processes at AMIRS, with 18 and 15 MeV protons, respectively, at a current of 20 ?A for 10 hours. The deposition of natSrCO3 on the Cu backing was carried out by means of the sedimentation method. Yt- trium-88 was separated in a 92 ? 5% radiochemical yield using the precipitation technique by precipitating natSr as SrSO4 (strontium-85 as a tracer) while radioyttrium passed through the filter paper. Also, a theoretical study of the nuclear reaction cross-sections for proton and deuteron induced reactions on natSr and natRb for the production of 88Y and 85Sr, respectively, was performed using the EMPIRE (version 3.1 Rivoli), TALYS-1.26 codes and the TENDL-2010 database.

New determinations of gamma-ray line intensities of the Ep=550 and 1747 keV resonances of the 13C(p,γ) 14N reaction

Gamma-ray angular distributions for the resonances at E p=550 and 1747 keV of the radiative capture reaction 13C(p,γ) 14N have been measured, using intense proton beams on isotopically pure 13C targets. Experimental gamma-ray spectra were obtained with three HP–Germanium detectors at four angles for E p=550 keV and six angles for E p=1747 keV in the range of 0–90° with respect to the proton beam. From the data, relative intensities for the strongest transitions were extracted with an accuracy of typically 5%, making these resonances new useful gamma-ray standards for efficiency calibration in the energy range from E γ=1.6–9 MeV. Gamma-ray branching ratios were obtained for several levels of 14N and are compared with literature values.

On the preparation of efficiency calibration standards for gamma-ray spectrometers

A procedure for preparation of low-activity efficiency calibration standards in different geometries and having different densities for gamma-ray spectrometers has been develpped. Natural organic and inorganic materials are used as matrices. The densities of the matrices used vary from 0.4 to 1.5 g/cm 3. The activity distribution homogeneity in the matrix after preparation and after using them for 9 months was studied. The matrix stability to settling down and selfgrinding in the process of continued usage is examined. The standards have been prepared using certified mixed-nuclide gamma-ray standard solutions, containing 241Am, 109Cd, 139Ce, 57Co, 60Co, 137Cs, 203Hg, 113Sn, 85Sr and 88Y and mono-nuclide solution containing 210Pb from EUROSTANDARD, traceable to the Czech Metrological Institute.

Gamma intensity standard from thermal neutron capture in 35Cl

Absolute emission probabilities of gamma-rays after thermal neutron capture in 35Cl were measured in the range 0.5–8.6 MeV. The intensities of 24 lines were determined with relative uncertainties below 3%. These data can usefully be employed as standards for efficiency calibration of gamma detectors and for the measurement of neutron capture cross sections by means of Ge detectors.

A reliable and accurate procedure for preparing low-activity efficiency calibration standards for germanium gamma-ray spectrometers

An empirical procedure is described which is readily capable of producing reliable and accurate efficiency calibration sources of low activity for high-resolution γ-ray spectrometers. Known activities of a multiisotopic solution are adsorbed onto a mixture of cation and anion-exchange resins and chromatographic-grade cellulose. The dried powder that results can be mixed with any desired solid natural matrix material to produce a homogeneous, extended geometry, efficiency calibration source. Results are presented which enable the method to be critically evaluated.

Alpha-emitting nuclides as absolute efficiency calibration sources for germanium detectors

Absolute intensities of γ-rays and K X-rays in the decays of 249Cf and 243Am− 239Np have been measured with high-resolution Ge detectors. Because of their long half-lives and ease of standardization by accurate alpha counting, these nuclides are recommended as standards for efficiency calibration of germanium detectors.

160Tb, 182Ta, and 192Ir as efficiency calibration standards for Ge(Li) detectors

Accurately measured energies and relative intensities of the gamma rays emitted in the decay of 160Tb, 182Ta and 192Ir are recommended for use as calibration standards for Ge(Li) detectors.

Long-lived standards for the efficiency calibration of Ge(Li) detectors

The intensities of the γ-rays and K X-rays associated with the decay of 249Cf, 243Am, 239Np and 243Cm were measured with respect to IAEA standards. Because of their long half-lives and ease of standardization by accurate alpha counting, these nuclides are recommended as standards for absolute efficiency calibration of Ge(Li) detectors.