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1.
S. S. Belyshev B. S. Ishkhanov V. V. Khankin A. A. Kuznetsov V. N. Orlin M. M. Popova K. A. Stopani 《Bulletin of the Russian Academy of Sciences: Physics》2018,82(6):702-707
The yields of photonuclear reactions on mixtures of natural isotopes of strontium and molybdenum that result in the formation and decay of bypassed nuclei 84Sr and 92Mo are measured and compared to theoretical results obtained using the TALYS code and calculations in the combined model of photonucleon reaction (CMPR). The need is demonstrated to consider isospin splitting in cases of photoproton reactions. The yields of the 92Mo(γ,p)91mNb, 84Sr(γ,p)83Rb reactions that make the main contribution to the formation and decay of 84Sr and 92Mo in the p-process of nucleosynthesis differ from the TALYS and CMPR results by several hundred percent. 相似文献
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3.
B. S. Ishkhanov I. M. Kapitonov A. A. Kuznetsov V. N. Orlin Han Dong Yoon 《Physics of Atomic Nuclei》2014,77(11):1362-1370
The results of experimentally and theoretically studying the photodisintegration of molybdenum isotopes are presented. The yields of various photonucleon reactions on stable molybdenum isotopes were determined by the gamma-activation method. Use was made of bremsstrahlung photons from an electron accelerator that were characterized by the endpoint energies of 19.5, 29.1, and 67.7 MeV. Reactions involving the emission of up to three nucleons from the target nucleus were observed. The experimental results in question were compared with theoretical predictions based on the combined photonucleon-reaction model and obtained for 15 molybdenum isotopes. The relations between basic photonucleon reactions on the molybdenum isotopes considered in our present study were explained. 相似文献
4.
B. S. Ishkhanov S. Yu. Troshchiev V. A. Chetvertkova 《Bulletin of the Russian Academy of Sciences: Physics》2012,76(4):481-485
Yields of photonuclear reaction on natural mixture of Sn isotopes irradiated by bremsstrahlung beam with maximum energy of
29.1 MeV are studied via the residual activity method. Using the TALYS code and a combined model, the cross sections of the
photonucleon reaction in stable isotopes of Sn are calculated. Measured yields are compared with the yields calculated using
theoretical, experimental, and estimated cross sections. 相似文献
5.
The induced-activity method is used to measure yields of photonuclear reactions induced in stable mercury isotopes by beams
of bremsstrahlung photons whose spectra have the endpoint energies of 19.5 and 29.1 MeV. On the basis of a collective model,
the partial cross sections and yields are calculated for photoproton and photoneutron reactions on these isotopes. The yields
calculated theoretically are compared with their measured counterparts. The possibility for the production in photonuclear
reactions of the bypassed nucleus 196Hg, which cannot be formed in astrophysical r and s processes, is analyzed. 相似文献
6.
S. S. Belyshev A. A. Kuznetsov K. A. Stopani V. V. Khankin 《Physics of Atomic Nuclei》2016,79(5):641-647
The gamma-activation technique was used to measure the absolute yields of photonuclear reactions on the cadmium isotopes 106,108Cd. The results obtained in this way were compared with the results of the calculations based on the statistical model. For reactions on the isotope 108Cd, agreement between these theoretical and experimental results is good, but the experimental ratio of the yields of photoproton and photoneutron reactions on the isotope 106Cd differs substantially from its theoretical counterpart. The results of our present study are discussed from the point of view of the production of bypassed nuclei in the p-process of nucleosynthesis. 相似文献
7.
B. S. Ishkhanov V. N. Orlin S. Yu. Troshchiev 《Moscow University Physics Bulletin》2011,66(2):135-141
Yields of photonucleon reactions of different multiplicity of natural isotopic mixture of Pb were measured on a bremsstrahlung
photon beam with a maximum energy of 67.7 MeV using gamma-activation methods. Cross-sections of photonucleon reactions of
different multiplicity were calculated on stable Pb isotopes within the bounds of the combined model. The calculated cross
sections are compared to those measured in experiments on quasimonochromatic photon beams. They are also used to split the
measured yields into yields of particular photonucleon reactions. 相似文献
8.
Cross sections were measured for (n,p) reactions on 92, 95, 96, 97, 98mo, (n, α) reactions on 92, 98Mo, and (n, 2n) reaction on 100Mo for the first time in the neutron energy range of 5.9 to 9.6 MeV. The quasi-monoenergetic neutrons were produced via the 2H(d, n)3He reaction using a deuterium gas target at a compact cyclotron. Use was made of the activation technique in combination with high-resolution γ-ray spectroscopy. Some systematic trends observed in the excitation functions are discussed. For the various isotopes of molybdenum, with increasing mass of the target nucleus, the thresholds of (n,p) and (n,α) reactions increase and the magnitudes of cross sections near the maxima of the excitation functions appear to decrease. Hauser-Feshbach calculations show that in general the excitation functions of (n, p) and (n, α) reactions are described within a factor of 2 by the statistical model only up to about 8 MeV; the (n,2n) reaction on 100Mo, however, is reproduced well from threshold up to 15 MeV by this model. 相似文献
9.
The neutron skin effect has been investigated for even isotopes of molybdenum at 25.6 MeV 94 − 100Mo(p, xn) reaction using the geometry-dependent hybrid model of pre-equilibrium nuclear reactions. Here the initial neutron/proton
exciton numbers were calculated from the neutron/ proton densities obtained from an effective nucleon–nucleon interaction
of the Skyrme type. Initial exciton numbers from different radii of even Mo isotopes were used to obtain the corresponding
neutron emission spectra. In this investigation the calculated results are compared with the experimental data as also with
each other. The results using central densities in the geometry-dependent hybrid model are in better agreement with the experimental
data. 相似文献
10.
S. S. Belyshev Y. A. Buvina B. S. Ishkhanov A. A. Kuznetsov V. N. Orlin K. A. Stopani V. V. Khankin 《Bulletin of the Russian Academy of Sciences: Physics》2018,82(6):608-613
Photonuclear reactions on a natural mixture of tin isotopes are studied by means of gamma activation. The experiment is performed using the bremsstrahlung γ-beam of an RTM55 racetrack microtron with a maximum electron energy of 55.6 MeV. The measured yields of photoproton and photoneutron reactions are compared to results from other experimental studies, and to calculations using the TALYS code and the combined model of photonucleon reactions (CMPR). 相似文献
11.
B. S. Ishkhanov S. Yu. Troshchiev 《Bulletin of the Russian Academy of Sciences: Physics》2011,75(4):566-568
Yields of photonuclear reactions on stable Hg isotopes under a bremsstrahlung photon beam with a maximum energy of 29.1 MeV
were measured using the induced activity method. Single-neutron and single-proton reactions and the 198Hg(γ,1p1n) reaction were observed. Photoneutron reaction yields with the production of metastable states were measured. 相似文献
12.
The yields of photonucleon reactions on the isotope 181Ta that are induced by bremsstrahlung photons whose endpoint energy is 67.7 MeV are measured by the residual-activity method.
The cross sections for photonucleon reactions on the isotope 181Ta are calculated on the basis of the TALYS code and a combined model. The measured reaction yields are compared with their
counterparts rescaled from cross sections obtained in experiments that employed beams of quasimonochromatic and bremsstrahlung
photons. The spectra of neutrons emitted from 181Ta nuclei after the absorption of photons having various energies are calculated within the TALYS code and the combined model
in question. 相似文献
13.
We have measured isomeric cross-section ratios for the photonuclear reactions 181Ta(γ, 3n) 178m,gTa, 142Nd(γ, n)141m,gNd, 110Pd(γ, n)109m1,m2,gPd, 108Pd(γ, n)107m1,m2Pd, 100Mo(γ, n) 99m,gMo, 92Mo(γ, n)91m,gMo and 89Y(γ, n)88m1,m2Y. The experimental results were compared with statistical model calculations according to the method of Huizenga and Vandenbosch. The applicability and limits of this method, especially the simple decision model for the population of the isomeric state and the ground state of the residual nucleus, were tested and discussed. Additionally, it is shown that for photonuclear reactions on magic nuclei, contributions of a direct reaction mechanism are not negligible. 相似文献
14.
An experiment on the irradiation of the natural mixture of 203,205Tl isotopes by the bremsstrahlung beam of pulsed racetrack microtron RTM-70 (Skobeltsyn Institute of Nuclear Physics, Moscow State University) at an electron energy of 67.7 MeV was performed. The yields and integral cross sections of multiparticle photonuclear reactions with 203,205Tl isotopes were measured. 相似文献
15.
J. R. H. Schneider S. Hofmann F. P. Heßberger G. Münzenberg W. Reisdorf P. Armbruster 《Zeitschrift für Physik A Hadrons and Nuclei》1983,312(1-2):21-26
In fusion evaporation reactions of a92Mo beam with targets of neutron deficient Rb — Mo isotopes very neutron deficient isotopes of elements between Au and Po have been produced. The new isotopes173, 174Au,175, 176Hg, and179Tl were identified by alpha spectroscopy. The mass excess value of176Hg could be linked to known values of theN?Z=16 chain. The location of the new isotopes with respect to the proton drip line is discussed. A new high energyα transition of (7.20±0.02) MeV andT 1/2=(1.4±0.5) ms has been found in the reaction92Mo+89Y→181Tl* at an excitation energy of 37 MeV. It is tentatively assigned to isotopes produced in 2-particle evaporation channels. 相似文献
16.
B. S. Ishkhanov V. N. Orlin S. Yu. Troischiev 《Moscow University Physics Bulletin》2010,65(6):471-476
Yields of photonuclear reactions of several Hg isotopes are measured on a bremsstrahlung photon beam with a maximal energy of 19.5 MeV using a gamma-activation analysis. Cross sections of photonuclear reactions on stable Hg isotopes are calculated within bonds of the collective model taking isospin splitting of giant dipole resonance into account. The experimental results are compared with the results of theoretical calculations and earlier experimental studies. 相似文献
17.
Tran Duc Thiep Truong Thi An Phan Viet Cuong Nguyen The Vinh Bui Minh Hue A. G. Belov O. D. Maslov G. V. Mishinsky V. I. Zhemenik 《Physics of Particles and Nuclei Letters》2017,14(1):102-111
We have determined the isomeric ratios of isomeric pairs 97m,gNb, 95m,gNb and 91m,gMo produced in 98Mo(γ, p)97m,gNb, 96Mo(γ, p)95m,gNb and 92Mo(γ, n)91m,gMo photonuclear reactions in the giant dipole resonance (GDR) region by the activation method. The results were analyzed, discussed and compared with the similar data from literature to examine the role of excitation energy, neutron configuration, channel effect and direct and pre-equilibrium processes in (γ, p) photonuclear reactions. In this work the isomeric ratios for 97m,gNb from 14 to 19 MeV, for 195m,gNb from14 to 24 MeV except 20 and 23.5 MeV and for 91m,gMo at 14 and 15 MeV are the first time measurements. 相似文献
18.
A. N. Ermakov B. S. Ishkhanov I. M. Kapitonov I. V. Makarenko V. N. Orlin 《Physics of Atomic Nuclei》2010,73(5):737-745
Experimental data on yields of multiparticle photonuclear reactions (involving the emission of up to seven neutrons from the
nucleus involved) on 197Au, 203,205Tl, and 209Bi nuclei in the region extending from the giant dipole resonance to an energy of 67.7 MeV are presented. These data are compared
with the results of modern theoretical calculations that take into account both the excitation of a giant dipole resonance
(GDR) in a nucleus and the photodisintegration of quasideutrons (QD) in it. By and large, experimental data confirm the results
of theoretical calculations—that is, only upon taking simultaneously into account both alternative photodisintegration mechanisms
(GDR excitation and QD photodisintegration) can one describe these experimental data. The contribution of QD photodisintegration
grows with increasing photon energy and neutron multiplicity and becomes dominant for reactions involving the emission of
not less than five neutrons from the nucleus being considered. The integrated cross sections for the processes in question
were estimated on the basis of simultaneously employing experimental yields of multinucleon photonuclear reactions and the
respective cross-section shapes calculated theoretically. 相似文献
19.
V. A. Varlachev A. A. Garapatskii G. N. Dudkin V. N. Padalko V. S. Skuridin E. S. Solodovnikov E. V. Chibisov 《Bulletin of the Russian Academy of Sciences: Physics》2008,72(3):319-323
Experiments on search for heavy neutron clusters in the reaction of induced fission of 235U nuclei by neutrons have been carried out on the nuclear reactor, using the activation method. Two hypothetical reactions have been investigated: 92Mo, 94Mo, 95Mo, 96Mo, 98Mo, 100Mo(xn, (x ? k)n)105Mo → 105Tc → 105Ru → 105Rh → 105Pd, with a minimum transfer of 5 to 13 neutrons to activated Mo isotopes, and 122Te(xn, (x ? k)n)122 + k Te → (β?) → 122 + k I, with a minimum transfer of 10 neutrons to activated 122Te isotope. Radiochemical methods for selecting technetium isotopes from molybdenum and iodine from tellurium were used. For the first reaction, the upper limit on the probability of neutron cluster formation was found to be P k ≤ 10?8 per fission. For the second reaction, indications to the existence of heavy neutron clusters were obtained. 相似文献
20.
O. A. Bessheiko L. A. Golinka-Bessheiko I. M. Kadenko 《Bulletin of the Russian Academy of Sciences: Physics》2008,72(6):757-760
The contribution from various channels of photonuclear reactions is considered to obtain parameters of the giant dipole resonance (GDR). It is pointed out that the channel with emission of charged particles is very important for some nuclei. GDR parameters for the 60Ni, 63Cu, and 64Zn nuclei are evaluated with allowance for all exit channels of photonuclear reactions. The EMPIRE-II code is used for theoretical calculations. 相似文献