Determination of activity of 51 Cr on gamma radiation measurements
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etermination of Activity of 51Cr on Gamma Radiation Measurements1, 2 V. V. Gorbachev*, V. N. Gavrin, T. V. Ibragimova, A. V. Kalikhov, Yu. M. Malyshkin, and A. A. Shikhin INR RAS, Moscow, 111312 Russia *e-mail: [email protected] Abstract—A method of determining the activity of intensive distributed β -sources on the measurement of the continuous spectrum of γ radiation, for example the internal bremsstrahlung, is developed. The recurrent formula for reconstructing of a continuous spectrum, registered in a Ge detector, at distorting it in the detector. The method of precise measurements of the spectrum of 51Cr internal bremsstrahlung using two point sources of low activity is described. DOI: 10.1134/S1063779616060113
1. INTRODUCTION
trino detectors SAGE and GALLEX with sources on basis of 51Cr and 37Ar isotopes with activities of 0.4– 1.8 МCi. The proposals of future source experiments on search of short base-line neutrino oscillations associated not only with measurements of gallium detectors (currently only gallium detector SAGE at the Baksan Neutrino Observatory of INR continues the measuring), but also with other detectors (e.g., BOREXINO [8]). One of the main sources of systematic uncertainties of the experiments with artificial neutrino sources is the error of determining the absolute activity of the source. In the three gallium calibration experiments with 51Cr sources main method of determining the source activity was the measurements of the heat released in decays (calorimetric method). The activity of an argon source in the SAGE calibration experiment was determined with approximately equal accuracy by several methods, based on the properties 37Ar as an ideal gas. In all proposals of new experiments are supposed to use the solid sources, so we can expect that the main method for measuring the activity will be also calorimetric method. However, in the new experiments the error of the method can be crucial for correct interpretation of the results, so an independent method of determining the activity with a comparable uncertainty is required. We have developed a new method for determining the activity of intense neutrino sources by measuring continuous spectra γ -radiation. Many neutrino β-sources emit γ -lines of certain energies. For example, 51Cr source emits 320 keV photons in 10% of decays. However, detected radiation of heterogeneous distributed source under the identical geometric efficiencies can be a different intensity, depending on the relative position of the source and detector. As shown
The determination of the status of neutrino oscillations with the parameter Δ m 2 ~ 1 eV2 is currently an actual task of neutrino physics. An indication of such oscillations were obtained in experiments with different neutrino sources: in the experiments LSND and MiniBooNE [1, 2] with muon neutrinos from accelerator, in gallium experiments with artificial sources of electron neutrinos SAGE [3, 4] and GALLEX [5, 6], in the experiments with electron antineutrinos from nuclear reactors [7]. It is expected that th
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