Cross sections for monitor reactions 27 Al(( p, x ) 24 Na, 27 Al( p, x ) 22 Na, and 27 Al( p, x ) 7 Be at proton energie
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CLEI Experiment
(p, x)24 Na, 27 Al(p, (p, x)22 Na, Cross Sections for Monitor Reactions 27 Al(p, (p, x)7 Be at Proton Energies in the Range 0.04–2.6 GeV and 27 Al(p, Yu. E. Titarenko, S. P. Borovlev, M. A. Butko, V. M. Zhivun, K. V. Pavlov, V. I. Rogov, A. Yu. Titarenko, R. S. Tikhonov, S. N. Florya, and A. B. Koldobskiy Institute for Theoretical and Experimental Physics, ul. Bol’shaya Cheremushkinskaya 25, Moscow, 117218 Russia Received October 7, 2010
Abstract—The cross sections for the monitor reactions 27 Al(p, x)24 Na, 27 Al(p, x)22 Na, and 27 Al(p, x)7 Be at 12 proton energies, 2605, 1598, 1199, 799, 600, 400, 249, 147.6, 97.2, 66.0, 44.6, and 40.8 MeV, have been determined with 72 × 72-mm square and 10.5-mm-diameter round aluminum foils. The rates of the reactions of the production of 24 Na, 22 Na, and 7 Be in the foils in each irradiation run have been determined by γ spectrometry, whereas the number of protons transmitted through these foils has been determined using calibrated fast current transformers. The cross sections have been determined as the ratios of the corresponding reaction to the average proton fluence. DOI: 10.1134/S1063778811040156
INTRODUCTION Common methods for the experimental determination of nuclide production cross sections are based on independent measurements of the rates of nuclear reactions and incident-particle fluences. The proton fluence is most often determined using monitor reactions. To obtain the cross sections for monitor reactions themselves, the corresponding product rates are measured by the γ-spectrometry method, whereas another method should be used to determine the proton fluence. Absolute measurements of particle fluences constitute one of the most difficult problems of experimental physics. The methods and instruments developed for such measurements are not universal and their reliability depends both on the radiation source operation mode and on the experimental conditions. Any changes require additional tests and adjustment of precision measuring instruments, significantly increasing a cost of measurements. In this study, the cross sections for monitor reactions 27 Al(p, x)24 Na, 27 Al(p, x)22 Na, and 27 Al(p, x)7 Be in the proton energy range of 0.04– 2.6 GeV are obtained as additional information from measurements of the cross sections for nuclide production in structural materials of electronuclear facilities (nat W, 181 Ta, 93 Nb, nat Ni, 56 Fe, and nat Cr) [1]. In all measurements, the number of protons was also measured using a fast current transformer. Such
an approach, combining the activation and current methods, provided the possibility to estimate the cross sections for monitor reactions with a rather high precision.
IRRADIATION OF EXPERIMENTAL SAMPLES The experimental samples were irradiated by protons with the energies of 2.6, 1.6, 1.2, 0.8, 0.6, 0.4, 0.25, 0.15, 0.1, 0.07, and 0.04 GeV in an extracted beam of the ITEP U-10 synchrotron, which is a ring accelerator, where 25-MeV protons are injected into the ring and the maximum energy of accelerated proto
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