نتایج جستجو برای: 7be concentrations
تعداد نتایج: 307122 فیلتر نتایج به سال:
over the past decades, the fallout radionuclides 137cs, 210pbex and 7be are increasingly being used to quantify soil erosion and sedimentation rates. although studies using 137cs and to some extent 210pbex are now well-documented, there is a need for further work aimed at exploring the use of 7be, particularly in arid and semi-arid areas. investigating soil erosion processes occurring over shor...
The results of the study on natural radionuclide content in 102 samples of the moss species randomly collected in 2008- 2013 at 30 locations of eastern Serbia are presented in the paper. The activity concentration values of 238U, 226Ra, 232Th, 40K, and 7Be determined by gamma spectrometry were within the intervals: 238U (1.1-50) Bq kg(-1), 226Ra (1.1-41) Bq kg(-1), 232Th (1.4-28) Bq kg(-1), 40K...
0031-9007= The 3He 4He; 7Be reaction plays an important role in determining the high energy solar neutrino flux and in understanding the abundances of primordial 7Li. This Letter reports a new precision measurement of the cross sections of this direct capture reaction, determined by measuring the ensuing 7Be activity in the region of Ec:m: 420 to 950 keV. Various recent theoretical fits to our ...
The cross sections for the (8B,7Be-p) breakup reaction on 58Ni and 208Pb targets at the beam energies of 25.8 MeV and 415 MeV have been calculated within a one-step prior-form distorted-wave Born approximation. The relative contributions of Coulomb and nuclear breakup of dipole and quadrupole multipolarities as well as their interference have been determined. The nuclear breakup contributions a...
Solar model predictions of 8B and p-p neutrinos agree with the experimentally determined fluxes (including oscillations): phi(pp)(measured)=(1.02+/-00.02+/-0.01)phi(pp)(theory) and phi(8B)(measured)=(0.88+/-0.04+/-0.23)phi(8B)(theory), 1sigma experimental and theoretical uncertainties, respectively. We use improved input data for nuclear fusion reactions, the equation of state, and the chemical...
We have measured the Coulomb dissociation of 8B into 7Be and proton at 254 MeV/nucleon using a large-acceptance focusing spectrometer. The astrophysical S17 factor for the 7Be(p,γ)8B reaction at Ec.m. = 0.25−2.78 MeV is deduced yielding S17(0) = 20.6± 1.2 (exp.) ± 1.0 (theo.) eV-b. This result agrees with the presently adopted zero-energy S17 factor obtained in directreaction measurements and w...
We present precision measurements of the 3He + 4He →7Be reaction in the range Ec.m. = 0.33 to 1.23 MeV using a small gas cell and detection of both prompt γ rays and 7Be activity. Our prompt and activity measurements are in good agreement within the experimental uncertainty of several percent. We find S(0) = 0.595 ± 0.018 keV b from fits of the Kajino theory to our data. We compare our results ...
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