Atlas of photoneutron cross sections obtained with monoenergetic photons
International Nuclear Information System (INIS)
Dietrich, S.S.; Berman, B.L.
1988-01-01
Photoneutron cross-section and integrated cross-section data obtained with monoenergetic photons are presented in a uniform format. All of the measured partial photoneutron cross sections, the total photoneutron cross section, and the photoneutron yield cross section are plotted as functions of the incident photon energy, as are the integrated photoneutron cross sections and their first and second moments. The values of the integrated cross sections and the moments of the integrated total cross section up to the highest photon energy for which they were measured are tabulated, as are the parameters of Lorentz curves fitted to the total photoneutron cross-section data for medium and heavy nuclei (A>50). This compilation is current as of June 1987. copyright 1988 Academic Press, Inc
Isotopic dependence of photoneutron cross sections around Strontium (Z=38) and Cesium (Z=55) nuclei
International Nuclear Information System (INIS)
Nakamura, T.; Uno, Y.; Yamadera, A.; Kase, T.
1992-01-01
We measured the average cross sections of (γ,n) reactions for 84 Sr, 86 Sr, 88 Sr, 85 Rb, 87 Rb, 98 Ru and 104 Ru isotopes in giant resonance region (9 to 25 MeV) using Bremsstrahlung radiation of 60 MeV maximum energy. We investigated the isotopic dependence of the average (γ,n) cross sections in giant resonance region from our experimental data and those estimated from other experimental data for Ge, Se, Zr, Mo, Sn, Te, Ce, Nd and Sm isotopes. As a result, we found that the average cross section data become highest for nuclei of neutron magic number of N = 50 and 82 except for Mo nucleus
New approach to analyzing and evaluating cross sections for partial photoneutron reactions
International Nuclear Information System (INIS)
Varlamov, V. V.; Ishkhanov, B. S.; Orlin, V. N.
2012-01-01
The presence of substantial systematic discrepancies between the results of different experiments devoted to determining cross sections for partial photoneutron reactions—first of all, (γ, n), (γ, 2n), and (γ, 3n) reactions—is a strong motivation for studying the reliability and authenticity of these data and for developing methods for taking into account and removing the discrepancies in question. In order to solve the first problem, we introduce objective absolute criteria involving transitional photoneutron-multiplicity functions F 1 , F 2 , F 3 , …; by definition, their values cannot exceed 1.0, 0.5, 0.33, …, respectively. With the aim of solving the second problem, we propose a new experimental-theoretical approach. In this approach, reaction cross sections are evaluated by simultaneously employing experimental data on the cross section for the total photoneutron yield, σ expt (γ, xn) = σ expt (γ, n) + 2σ expt (γ, 2n) + 3σ expt (γ, 3n) + …, which are free from drawbacks plaguing experimental methods for sorting neutrons in multiplicity, and the results obtained by calculating the functions F theor 1 , F theor 2 , F theor 3 , … on the basis of the modern model of photonuclear reactions. The reliability and authenticity of data on the cross sections for (γ, n), (γ, 2n), and (γ, 3n) partial reactions—σ eval (γ, in) = F i theor σ expt (γ, xn)—were evaluated for the 90 Zr, 115 In, 112,114,116,117,118,119,120,122,124 Sn, 159 Tb, and 197 Au nuclei.
Neutron total cross section measurements of gold and tantalum at the nELBE photoneutron source
Hannaske, Roland; Beyer, Roland; Junghans, Arnd; Bemmerer, Daniel; Birgersson, Evert; Ferrari, Anna; Grosse, Eckart; Kempe, Mathias; Kögler, Toni; Marta, Michele; Massarczyk, Ralph; Matic, Andrija; Schramm, Georg; Schwengner, Ronald; Wagner, Andreas
2014-01-01
Neutron total cross sections of 197 Au and nat Ta have been measured at the nELBE photoneutron source in the energy range from 0.1 - 10 MeV with a statistical uncertainty of up to 2 % and a total systematic uncertainty of 1 %. This facility is optimized for the fast neutron energy range and combines an excellent t ime structure of the neutron pulses (electron bunch width 5 ps) with a short flight path of 7 m. Because of the low instantaneous neutron flux transmission measurements of neutron total cross sections are possible, that exhibit very different beam and back ground conditions than found at other neutron sources.
Energy Technology Data Exchange (ETDEWEB)
Varlamov, V.V. [Lomonosov Moscow State University, Skobeltsyn Institute of Nuclear Physics, Moscow (Russian Federation); Davydov, A.I. [Lomonosov Moscow State University, Physics Faculty, Moscow (Russian Federation); Ishkhanov, B.S. [Lomonosov Moscow State University, Skobeltsyn Institute of Nuclear Physics, Moscow (Russian Federation); Lomonosov Moscow State University, Physics Faculty, Moscow (Russian Federation)
2017-09-15
Data on partial photoneutron reaction cross sections (γ, 1n), (γ, 2n), and (γ, 3n) for {sup 59}Co obtained in two experiments carried out at Livermore (USA) were analyzed. The sources of radiation in both experiments were the monoenergetic photon beams from the annihilation in flight of relativistic positrons. The total yield was sorted by the neutron multiplicity, taking into account the difference in the neutron energy spectra for different multiplicity. The two quoted studies differ in the method of determining the neutron. Significant systematic disagreements between the results of the two experiments exist. They are considered to be caused by large systematic uncertainties in partial cross sections, since they do not satisfy physical criteria for reliability of the data. To obtain reliable cross sections of partial and total photoneutron reactions a new method combining experimental data and theoretical evaluation was used. It is based on the experimental neutron yield cross section which is rather independent of neutron multiplicity and the transitional neutron multiplicity functions of the combined photonucleon reaction model (CPNRM). The model transitional multiplicity functions were used for the decomposition of the neutron yield cross section into the contributions of partial reactions. The results of the new evaluation noticeably differ from the partial cross sections obtained in the two experimental studies are under discussion. (orig.)
Photoneutron multiplicities of preactinide nuclei at energies above the pion threshold
International Nuclear Information System (INIS)
Arruda-Neto, J.D.T.; Simionatto, S.; Likhachev, V.P.; Garcia, F.; Mesa, J.
1998-01-01
The average photoneutron multiplicities anti ν of Au, Ta and 182 W were deduced from their previously measured excitation energies anti E x , from 160 to 250 MeV. A combined analysis of these data and those measured at Saclay up to 140 MeV allowed the extraction of information on anti E x at the ''pure evaporation'' and quasideuteron energy regions. A theoretical approach for the study of anti ν above 140 MeV, which incorporates photopion reabsorption processes by two-body, was proposed, allowing a tentative delineation of the pion mean free path in the nucleus. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Goryachev, A M; Zalesnyi, G N [Saratovskii Gosudarstvennyi Univ. (USSR); Tulupov, B A [AN SSSR, Moscow. Inst. Yadernykh Issledovanii
1975-01-01
Photoneutron cross-sections for /sup 64/,/sup 66/,/sup 68/Zn, /sup 70/,/sup 72/,/sup 74/,/sup 76/Ge, and /sup 76/,/sup 78/,/sup 80/,/sup 82/Se nuclei from the threshold energy to 24 MeV with 0.2 MeV step have been measured. Results of the experiment are compared to predictions of the collective dynamical model of a giant resonance.
Photoneutron cross sections for D2O and beryllium
International Nuclear Information System (INIS)
Bowsher, H.F.; Woods, F.J.; Baumann, N.P.
1975-01-01
The photodissociation cross section by 24 Na gamma rays was measured for deuterium in order to resolve a discrepancy between earlier measurements (1.43 to 1.59 millibarns) and a more recently reported one (1.34 mb). The measurement of the beryllium (γ,n) cross section for 24 Na gamma rays was also included as a check. Results for deuterium (1.54 mb) are in agreement with the earlier values
Photoneutron and Photonuclear Cross Sections According to Packed cluster Model
International Nuclear Information System (INIS)
El-Mekkawi, L.S.; El-Bakty, O.M.
1998-01-01
Photonuclear gross sections have been estimated for 232 Th, 237 Np, 239 Pu, 233 U, 234 U, 235 U, 238 U in the energy range from threshold up to 20 MeV, by perturbation balance in Packed Cluster. The Packed Cluster (gamma, f) and (gamma, n) cross sections require complete absence of any (gamma,2n) or (gamma,nf) cross sections for 233 U and 234 U as in experiment. It also explains the early (gamma,n) and gamma,nf) reactions in 235 U
Photo-neutron cross sections for unstable neutron-rich oxygen isotopes
International Nuclear Information System (INIS)
Leistenschneider, A.; Aumann, T.; Boretzky, K.
2001-05-01
The dipole response of stable and unstable neutron-rich oxygen nuclei of masses A = 17 to A = 22 has been investigated experimentally utilizing electromagnetic excitation in heavy-ion collisions at beam energies around 600 MeV/nucleon. A kinematically complete measurement of the neutron decay channel in inelastic scattering of the secondary beam projectiles from a Pb target was performed. Differential electromagnetic excitation cross sections dσ/dE were derived up to 30 MeV excitation energy. In contrast to stable nuclei, the deduced dipole strength distribution appears to be strongly fragmented and systematically exhibits a considerable fraction of low-lying strength, exhausting up to 12% of the energy-weighted dipole sum rule at excitation energies below 15 MeV. (orig.)
Photoneutron cross sections measurements in 9Be, 13C e 17O with thermal neutron capture gamma-rays
International Nuclear Information System (INIS)
Semmler, Renato
2006-01-01
Photoneutron cross sections measurements of 9 Be, 13 C and 17 O have been obtained in the energy interval between 1,6 and 10,8 MeV, using neutron capture gamma-rays with high resolution in energy (3 a 21 eV), produced by 21 target materials, placed inside a tangential beam port, near the core of the IPEN/CNEN-SP IEA-R1 (5 MW) research reactor. The samples have been irradiated inside a 4π geometry neutron detector system 'Long Counter', 520,5 cm away from the capture target. The capture gamma-ray flux was determined by means of the analysis of the gamma spectrum obtained by using a Ge(Li) solid-state detector (EG and G ORTEC, 25 cm 3 , 5%), previously calibrated with capture gamma-rays from a standard target of Nitrogen (Melamine). The neutron photoproduction cross section has been measured for each target capture gamma-ray spectrum (compound cross section). A inversion matrix methodology to solve inversion problems for unfolding the set of experimental compound cross sections, was used in order to obtain the cross sections at specific excitation energy values (principal gamma line energies of the capture targets). The cross sections obtained at the energy values of the principal gamma lines were compared with experimental data reported by other authors, with have employed different gamma-ray sources. A good agreement was observed among the experimental data in this work with reported in the literature. (author)
International Nuclear Information System (INIS)
Varlamov, V.V.; Efimkin, N.G.; Ishkhanov, B.S.; Sapunenko, V.V.; Stepanov, M.E.
1993-01-01
The method based on the method of reduction is proposed for the evaluation of photonuclear reaction cross sections have been obtained at significant systematic uncertainties (different apparatus functions, calibration and normalization uncertainties). The evaluation method consists of using the real apparatus function (photon spectrum) of each individual experiment to reduce the data to a representation generated by an apparatus function of better quality. The task is to find the most reasonably achievable monoenergetic representation (MRAMR) of the information about cross section contained in different experiment observables and to take into account the experimental uncertainties of calibration and normalization procedures. The method was used to obtain the evaluated total photoneutron (γ, xn) reaction cross sections for 16 O, 28 Si, nat Cu, 141 Pr, and 208 Pb are presented. 79 refs., 19 figs., 6 tabs
Capture cross sections on unstable nuclei
Tonchev, A. P.; Escher, J. E.; Scielzo, N.; Bedrossian, P.; Ilieva, R. S.; Humby, P.; Cooper, N.; Goddard, P. M.; Werner, V.; Tornow, W.; Rusev, G.; Kelley, J. H.; Pietralla, N.; Scheck, M.; Savran, D.; Löher, B.; Yates, S. W.; Crider, B. P.; Peters, E. E.; Tsoneva, N.; Goriely, S.
2017-09-01
Accurate neutron-capture cross sections on unstable nuclei near the line of beta stability are crucial for understanding the s-process nucleosynthesis. However, neutron-capture cross sections for short-lived radionuclides are difficult to measure due to the fact that the measurements require both highly radioactive samples and intense neutron sources. Essential ingredients for describing the γ decays following neutron capture are the γ-ray strength function and level densities. We will compare different indirect approaches for obtaining the most relevant observables that can constrain Hauser-Feshbach statistical-model calculations of capture cross sections. Specifically, we will consider photon scattering using monoenergetic and 100% linearly polarized photon beams. Challenges that exist on the path to obtaining neutron-capture cross sections for reactions on isotopes near and far from stability will be discussed.
Capture cross sections on unstable nuclei
Directory of Open Access Journals (Sweden)
Tonchev A.P.
2017-01-01
Full Text Available Accurate neutron-capture cross sections on unstable nuclei near the line of beta stability are crucial for understanding the s-process nucleosynthesis. However, neutron-capture cross sections for short-lived radionuclides are difficult to measure due to the fact that the measurements require both highly radioactive samples and intense neutron sources. Essential ingredients for describing the γ decays following neutron capture are the γ-ray strength function and level densities. We will compare different indirect approaches for obtaining the most relevant observables that can constrain Hauser-Feshbach statistical-model calculations of capture cross sections. Specifically, we will consider photon scattering using monoenergetic and 100% linearly polarized photon beams. Challenges that exist on the path to obtaining neutron-capture cross sections for reactions on isotopes near and far from stability will be discussed.
Low level photoneutron detection equipment
International Nuclear Information System (INIS)
Ji Changsong; Zhang Yuqin; Li Yuansui
1991-01-01
A low level photoneutron detection equipment has been developed. The photoneutrons produced by interaction of 226 Ra gamma quanta and deutron (D) target are detected with n-n discrimination detector made up of 3 He proportional counter array. The D-content information in the target can be obtained from the measured photoneutron counts. The equipment developed is mainly used for nondestructive D-content measurement of D-devices
International Nuclear Information System (INIS)
Naik, H.; Kim, G.N.; Schwengner, R.; Kim, K.; Zaman, M.; Tatari, M.; Sahid, M.; Yang, S.C.; John, R.; Massarczyk, R.; Junghans, A.; Shin, S.G.; Key, Y.; Wagner, A.; Lee, M.W.; Goswami, A.; Cho, M.-H.
2013-01-01
The photo-neutron cross-sections of 93 Nb at the end-point bremsstrahlung energies of 12, 14 and 16 MeV as well as 45, 50, 55, 60 and 70 MeV have been determined by the activation and the off-line γ-ray spectrometric techniques using the 20 MeV electron linac (ELBE) at Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Dresden, Germany, and 100 MeV electron linac at Pohang Accelerator Laboratory (PAL), Pohang, Korea. The 93 Nb(γ, xn, x=1–4) reaction cross-sections as a function of photon energy were also calculated using computer code TALYS 1.4. The flux-weighted average values were obtained from the experimental and the theoretical (TALYS) values based on mono-energetic photons. The experimental values of present work are in good agreement with the flux-weighted theoretical values of TALYS 1.4 but are slightly higher than the flux-weighted experimental data of mono-energetic photons. It was also found that the theoretical and the experimental values of present work and literature data for the 93 Nb(γ, xn) reaction cross-sections increase from the threshold values to a certain energy, where other reaction channels opens. However, the increase of 93 Nb(γ, n) and 93 Nb(γ, 2n) reaction cross-sections are sharper compared to 93 Nb(γ, 3n) and 93 Nb(γ, 4n) reaction cross-sections. The sharp increase of 93 Nb(γ, n) and 93 Nb(γ, 2n) reaction cross-sections from the threshold value up to 17–22 MeV is due to the Giant Dipole Resonance (GDR) effect besides the role of excitation energy. After a certain values, the individual 93 Nb(γ, xn) reaction cross-sections decrease with increase of bremsstrahlung energy due to opening of other reaction channels
94 Mo(γ,n) and 90Zr(γ,n) cross-section measurements towards understanding the origin of p-nuclei
Meekins, E.; Banu, A.; Karwowski, H.; Silano, J.; Zimmerman, W.; Muller, J.; Rich, G.; Bhike, M.; Tornow, W.; McClesky, M.; Travaglio, C.
2014-09-01
The nucleosynthesis beyond iron of the rarest stable isotopes in the cosmos, the so-called p-nuclei, is one of the forefront topics in nuclear astrophysics. Recently, a stellar source was found that, for the first time, was able to produce both light and heavy p-nuclei almost at the same level as 56Fe, including the most debated 92,94Mo and 96,98Ru; it was also found that there is an important contribution from the p-process nucleosynthesis to the neutron magic nucleus 90Zr. We focus here on constraining the origin of p-nuclei through nuclear physics by studying two key astrophysical photoneutron reaction cross sections for 94Mo(γ,n) and 90Zr(γ,n). Their energy dependencies were measured using quasi-monochromatic photon beams from Duke University's High Intensity Gamma-ray Source facility at the respective neutron threshold energies up to 18 MeV. Preliminary results of these experimental cross sections will be presented along with their comparison to predictions by a statistical model based on the Hauser-Feshbach formalism implemented in codes like TALYS and SMARAGD. The nucleosynthesis beyond iron of the rarest stable isotopes in the cosmos, the so-called p-nuclei, is one of the forefront topics in nuclear astrophysics. Recently, a stellar source was found that, for the first time, was able to produce both light and heavy p-nuclei almost at the same level as 56Fe, including the most debated 92,94Mo and 96,98Ru; it was also found that there is an important contribution from the p-process nucleosynthesis to the neutron magic nucleus 90Zr. We focus here on constraining the origin of p-nuclei through nuclear physics by studying two key astrophysical photoneutron reaction cross sections for 94Mo(γ,n) and 90Zr(γ,n). Their energy dependencies were measured using quasi-monochromatic photon beams from Duke University's High Intensity Gamma-ray Source facility at the respective neutron threshold energies up to 18 MeV. Preliminary results of these experimental cross
Multilevel parametrization of fissile nuclei resonance cross sections
International Nuclear Information System (INIS)
Lukyanov, A.A.; Kolesov, V.V.; Janeva, N.
1987-01-01
Because the resonance interference has an important influence on the resonance structure of neutron cross sections energy dependence at lowest energies, multilevel scheme of the cross section parametrization which take into account the resonance interference is used for the description with the same provisions in the regions of the interferential maximum and minimum of the resonance cross sections of the fissile nuclei
Total dissociation cross section of halo nuclei
Energy Technology Data Exchange (ETDEWEB)
Formanek, J. [Karlova Univ., Prague (Czech Republic). Fakulta Matematicko-Fyzikalni; Lombard, R.J. [Paris-11 Univ., 91 - Orsay (France). Inst. de Physique Nucleaire
1996-10-01
Calculations of the total dissociation cross section is performed in the impact parameter representation. The case of {sup 11}Be and {sup 11}Li loosing one and two neutron(s), respectively, by collision on a {sup 12}C target, which remains in its ground state are discussed. The results are found to depend essentially on the rms radius of the halo wave function. (author). 12 refs.
Solid state nuclear magnetic resonance studies of cross polarization from quadrupolar nuclei
Energy Technology Data Exchange (ETDEWEB)
De Paul, Susan M. [Univ. of California, Berkeley, CA (United States)
1997-08-01
The development of solid-state Nuclear Magnetic Resonance (NMR) has, to a large extent, focused on using spin-1/2 nuclei as probes to investigate molecular structure and dynamics. For such nuclei, the technique of cross polarization is well-established as a method for sensitivity enhancement. However, over two-thirds of the nuclei in the periodic table have a spin-quantum number greater than one-half and are known as quadrupolar nuclei. Such nuclei are fundamental constituents of many inorganic materials including minerals, zeolites, glasses, and gels. It is, therefore, of interest to explore the extent to which polarization can be transferred from quadrupolar nuclei. In this dissertation, solid-state NMR experiments involving cross polarization from quadrupolar nuclei to spin-1/2 nuclei under magic-angle spinning (MAS) conditions are investigated in detail.
Advanced modeling of reaction cross sections for light nuclei
International Nuclear Information System (INIS)
Resler, D.A.
1991-01-01
The shell model/R-matrix technique of calculating nuclear reaction cross sections for light projectiles incident on light nuclei is discussed, particularly in the application of the technique to thermonuclear reactions. Details are presented on the computational methods for the shell model which display how easily the calculations can be performed. Results of the shell model/R-matrix technique are discussed as are some of the problems encountered in picking an appropriate nucleon-nucleon interaction for the large model spaces which must be used for current problems. The status of our work on developing an effective nucleon-nucleon interaction for use in large-basis shell model calculations is presented. This new interaction is based on a combination of global constraints and microscopic nuclear data. 23 refs., 6 figs., 2 tabs
Energy Technology Data Exchange (ETDEWEB)
Greschner, Martin
2013-07-01
The Institute for Nuclear and Particle Physics at the Technische Universitaet Dresden (TUD) has build a neutron physics laboratory at Forschungszentrum Dresden-Rossendorf (FZD) to investigate nuclear processes in materials. The experiments are focused on materials relevant to nuclear fusion. The laboratory is equipped with three intensive neutron sources. The first is a 14 MeV monochromatic neutron source based on the DT reaction (owned by TUD); the other two are continuous and pulsed white photoneutron sources based on (γ,xn) reactions. One pulsed photoneutron source is realized by FZD in cooperation with the TUD. The continuous photoneutron source utilises a tungsten radiator (Tungsten Photoneutron Source) to produce neutrons with a wide energy spectra. The TPNS uses the ELBE-accelerator as a source of electrons for neutron production. This process involves an intermediate step, where slowed down electrons produce bremsstrahlung (γ-rays) absorbed by tungsten nuclei. Consecutively, the excited nuclei emit neutrons. The neutron flux of the photoneutron source is five orders of magnitude higher than the flux of the DT neutron sources with appropriate moderation. The neutron spectrum of TPNS can be modified by moderators, in such a way that the spectrum is comparable to that in the first wall of a Tokamak-Reactor. That allows investigations with the typical neutron spectrum of the fusion reactor. The technical solution, initial operation and the first experiment are described in this work. The neutron source is, in particular, dedicated to quantitative investigations in fusion neutronics. A fusion reactor produces radioactive isotopes as a nuclear waste. The main activity is accumulated in the structural materials. Carefully selected structural materials can significantly minimize the activity and thereby the amount of nuclear waste. The purpose of this project is to find constructional materials with half-lives shorter than several years, which can be recycled
Directory of Open Access Journals (Sweden)
Minkov N.
2016-01-01
Full Text Available We study the effects of quadrupole-octupole deformations on the energy and magnetic properties of high-K isomeric states in even-even heavy and superheavy nuclei. The neutron two-quasiparticle (2qp isomeric energies and magnetic dipole moments are calculated within a deformed shell model with the Bardeen-Cooper- Schrieffer (BCS pairing interaction over a wide range of quadrupole and octupole deformations. We found that in most cases the magnetic moments exhibit a pronounced sensitivity to the octupole deformation, while the 2qp energies indicate regions of nuclei in which the presence of high-K isomeric states may be associated with the presence of octupole softness or even with octupole deformation. In the present work we also examine the influence of the BCS pairing strength on the energy of the blocked isomer configuration. We show that the formation of 2qp energy minima in the space of quadrupole-octupole and eventually higher multipolarity deformations is a subtle effect depending on nuclear pairing correlations.
International Nuclear Information System (INIS)
Lepretre, A.
1982-06-01
The total photonuclear absorption cross section for Sn, Ce, Ta, Pb and U has been studied from 25 to 140 MeV using a continuously variable monochromatic photon beam obtained from the annihilation in flight of monoenergetic positrons. The basic experimental results are a set of data giving sums of inclusive multiple photoneutron production cross sections of the form σsup(j) (Esub(γ) = Σsub(i=j)σ(γ,in) for neutron multiplicities ranging from j=1 to 12. From these data the total photonuclear absorption cross section σ(tot : Esub(γ)) has been deduced. It is concluded that Levinger's modified quasi-deuteron model describes the total cross sections reasonably well. When these data are combined with lower energy data and integrated to 140 MeV they indicate the need for an enhancement factor K for the Thomas-Reiche-Kuhn sum rule of 0.76+-0.10. No evidence was found that would indicate an A-dependence for the enhancement factor. From event-by-event records of observed photoneutron multiplicities it was also possible to determine the mean number of photoneutrons, antiν, for each photon energy and the widths W of the multiplicities distributions. From these measurements one also obtains the cross section for the formation of a compound nucleus state excited with the full energy of the absorbed photon [fr
Measurement of total reaction cross sections of exotic neutron rich nuclei
International Nuclear Information System (INIS)
Mittig, W.; Chouvel, J.M.; Wen Long, Z.
1987-01-01
Total reaction cross-sections of neutron rich nuclei from C to Mg in a thick Si-target have been measured using the detection of the associated γ-rays in a 4Π-geometry. This cross-section strongly increases with neutron excess, indicating an increase of as much as 15% of the reduced strong absorption radius with respect to stable nuclei
A photoneutron production option for MCNP4A
International Nuclear Information System (INIS)
Gallmeier, F.X.
1996-01-01
A photoneutron production option was implemented in the MCNP4A code, mainly to supply a tool for reactor shielding calculations in beryllium and heavy water environments of complicated three dimensional geometries. Subroutines were developed to calculate the probability of the photoneutron production at the photon collision sites and the energy and flight direction of the created photoneutrons with the help of user supplied data. These subroutines are accessed through subroutine colidp which processes the photon collisions
Curves and tables of neutron cross sections of fission product nuclei in JENDL-3
Energy Technology Data Exchange (ETDEWEB)
Nakagawa, Tsuneo [ed.
1992-06-15
Neutron cross sections of 172 nuclei in the fission product region stored in JENDL-3 are shown in graphs and tables. The evaluation work of these nuclei was made by the Fission Product Nuclear Data Working Group of the Japanese Nuclear Data Committee, in the neutron energy region from 10{sup {minus}5} eV to 20 MeV. Almost of the cross section data reproduced in graphs in this report. The cross section averaged over 38 energy intervals are listed in a table. Shown in order tables are thermal cross sections, resonance integrals, Maxwellian neutron flux average cross sections, fission spectrum average cross sections, 14-MeV cross sections, one group average cross sections in neutron flux of typical types of fission reactors and average cross sections in the 30-keV Maxwellian spectrum.
Curves and tables of neutron cross sections of fission product nuclei in JENDL-3
International Nuclear Information System (INIS)
Nakagawa, Tsuneo
1992-06-01
Neutron cross sections of 172 nuclei in the fission product region stored in JENDL-3 are shown in graphs and tables. The evaluation work of these nuclei was made by the Fission Product Nuclear Data Working Group of the Japanese Nuclear Data Committee, in the neutron energy region from 10 -5 eV to 20 MeV. Almost all the cross section data are reproduced in graphs in this report. The cross section averaged over 38 energy intervals are listed in a table. Shown in other tables are thermal cross sections, resonance integrals, Maxwellian neutron flux average cross sections, fission spectrum average cross sections, 14-MeV cross sections, one group average cross sections in neutron flux of typical types of fission reactors and average cross sections in the 30-keV Maxwellian spectrum. (author)
Parametrization of the cross sections for complete disintegration of nuclei at relativistic energies
International Nuclear Information System (INIS)
Bogdanov, V.G.; Plyushchev, V.A.; Solov'eva, Z.I.
1988-01-01
A phenomenological analysis of observations of the complete disintegration of target nuclei in emulsions in relativistic heavy-ion reactions is given. On the basis of the probability of complete disintegration obtained from the observations it is possible to determine the value of the disintegration cross sections. A parametrizatio of these inelastic cross sections is formulated
On the threshold sensitivity of low background photoneutron systems
International Nuclear Information System (INIS)
Kazakevich, G.M.; Ponomarchuk, V.A.; Filippov, E.M.
1973-01-01
A mathematical substantiation is given of determining the sensitivity threshold for a number of photoneutron devices used in practice (Berill-2, Berill-4 etc.). It is shown that, considering various effects and a real time of measurements, the sensitivity threshold of the photoneutron devices waries within the range of 1.3x10 -3 % (Berill-3) to 2.2x10 -5 %
Polarization of photoneutrons from the threshold region of 208Pb
International Nuclear Information System (INIS)
Holt, R.J.; Jackson, H.E.
1975-01-01
In order to determine the parities of several resonances in 208 Pb, the polarization of photoneutrons from the 208 Pb(γ,n(pol)) 207 Pb reaction was measured. This represents the first measurement of the polarization of photoneutrons from resonances near threshold. The observations are tabulated. (SDF)
Cross sections of the interactions of He nuclei with protons
International Nuclear Information System (INIS)
Glagolev, V.V.; Lebedev, R.M.; Pestova, G.D.; Shimansky, S.S.; Kravcikova, M.; Seman, M.; Sandor, L.; Dirner, A.; Hlavacova, J.; Martinska, G.; Urban, J.; Khairetdinov, K.U.; Braun, H.; Gerber, J.P.; Juillot, P.; Michalon, A.; Kacharava, A.K.; Menteshashvili, Z.P.; Nioradze, M.S.; Salukvadze, Z.R.; Sobczak, T.; Stepaniak, J.
1993-01-01
4 He-p collisions at two values of 4 He momenta 8.6 GeV/c and 13.6 GeV/c as well as the 3 He-p collisions at 13.5 GeV/c have been studied using the one-meter JINR hydrogen bubble chamber. Total, elastic, topological and reaction cross sections have been measured. The cross sections have been determined on a sample of minimum biased events. (orig.)
Charged current cross section for massive cosmological neutrinos impinging on radioactive nuclei
Energy Technology Data Exchange (ETDEWEB)
Lazauskas, R.; Volpe, C. [Institut de Physique Nuclueaire, 91 - Orsay (France); Vogel, P. [Kellogg Radiation Lab., Caltech, Pasadena, California (United States)
2007-07-01
We discuss the cross section formula both for massless and massive neutrinos on stable and radioactive nuclei. The latter could be of interest for the detection of cosmological neutrinos whose observation is one of the main challenges of modern cosmology. We analyze the signal to background ratio as a function of the ratio m{nu}/{delta}, i.e. the neutrino mass over the detector resolution and show that an energy resolution {delta} {<=} 0.5 eV would be required for sub-eV neutrino masses, independently of the gravitational neutrino clustering. Finally we mention the non-resonant character of neutrino capture on radioactive nuclei. (authors)
On a calculation of nucleon knock-out cross sections in a collision of relativistic nuclei
International Nuclear Information System (INIS)
Goryachev, B.I.; Lin'kova, N.V.
1985-01-01
It is shown that in the framework of the two-stage model one can obtain knock-out cross sections of the given number of nucleons from the nucleus-target at a certain number of nucleons knocked out from the nucleus-projectile. The first stage is considered as a fast process of nucleon collisions of interacting nuclei which is completed with knock out of one or several nucleons. The second stage-comparatively slow - is related to de-excitation of nuclei-fragments
Calculations of the giant-dipole-resonance photoneutrons using a coupled EGS4-morse code
International Nuclear Information System (INIS)
Liu, J.C.; Nelson, W.R.; Kase, K.R.; Mao, X.S.
1995-10-01
The production and transport of the photoneutrons from the giant-dipoleresonance reaction have been implemented in a coupled EGS4-MORSE code. The total neutron yield (including both the direct neutron and evaporation neutron components) is calculated by folding the photoneutron yield cross sections with the photon track length distribution in the target. Empirical algorithms based on the measurements have been developed to estimate the fraction and energy of the direct neutron component for each photon. The statistical theory in the EVAP4 code, incorporated as a MORSE subroutine, is used to determine the energies of the evaporation neutrons. These represent major improvements over other calculations that assumed no direct neutrons, a constant fraction of direct neutrons, monoenergetic direct neutron, or a constant nuclear temperature for the evaporation neutrons. It was also assumed that the slow neutrons ( 2 θ, which have a peak emission at 900. Comparisons between the calculated and the measured photoneutron results (spectra of the direct, evaporation and total neutrons; nuclear temperatures; direct neutron fractions) for materials of lead, tungsten, tantalum and copper have been made. The results show that the empirical algorithms, albeit simple, can produce reasonable results over the interested photon energy range
Photoneutron Reaction Data for Nuclear Physics and Astrophysics
Directory of Open Access Journals (Sweden)
Utsunomiya Hiroaki
2018-01-01
Full Text Available We discuss the role of photoneutron reaction data in nuclear physics and astrophysics in conjunction with the Coordinated Research Project of the International Atomic Energy Agency with the code F41032 (IAEA-CRP F41032.
Photoneutron Reaction Data for Nuclear Physics and Astrophysics
Utsunomiya, Hiroaki; Renstrøm, Therese; Tveten, Gry Merete; Gheorghe, Ioana; Filipescu, Dan Mihai; Belyshev, Sergey; Stopani, Konstantin; Wang, Hongwei; Fan, Gongtao; Lui, Yiu-Wing; Symochko, Dmytro; Goriely, Stephane; Larsen, Ann-Cecilie; Siem, Sunniva; Varlamov, Vladimir; Ishkhanov, Boris; Glodariu, Tudor; Krzysiek, Mateusz; Takenaka, Daiki; Ari-izumi, Takashi; Amano, Sho; Miyamoto, Shuji
2018-05-01
We discuss the role of photoneutron reaction data in nuclear physics and astrophysics in conjunction with the Coordinated Research Project of the International Atomic Energy Agency with the code F41032 (IAEA-CRP F41032).
Fusion-fission probabilities, cross sections, and structure notes of superheavy nuclei
International Nuclear Information System (INIS)
Kowal, Michał; Cap, Tomasz; Jachimowicz, Piotr; Skalski, Janusz; Siwek-Wilczyńska, Krystyna; Wilczyński, Janusz
2016-01-01
Fusion – fission probabilities in the synthesis of heaviest elements are discussed in the context of the latest experimental reports. Cross sections for superheavy nuclei are evaluated using the “Fusion by Diffusion” (FBD) model. Predictive power of this approach is shown for experimentally known Lv and Og isotopes and predictions given for Z = 119, 120. Ground state and saddle point properties as masses, shell corrections, pairing energies, and deformations necessary for cross-section estimations are calculated systematically within the multidimensional microscopic-macroscopic method based on the deformed Woods-Saxon single-particle potential. In the frame of the FBD approach predictions for production of elements heavier than Z = 118 are not too optimistic. For this reason, and because of high instability of superheavy nuclei, we comment on some structure effects, connected with the K-isomerism phenomenon which could lead to a significant increase in the stability of these systems.
International Nuclear Information System (INIS)
Kloss, Yu.Yu.
1985-01-01
Program package and numerical solution of the problem for a system of coupled equations used in optical model to solve a problem on low and mean energy neutron scattering on deformed nuclei, is considered. With these programs differnet scattering cross sections depending on the incident neutron energy on even-even and even-odd nuclei were obtained. The programm permits to obtain different scattering cross sections (elastic, inelastic), excitation cross sections of the first three energy levels of rotational band depending on the energy, angular distributions and neutron polarizations including excited channels. In the program there is possibility for accounting even-even nuclei octupole deformation
Energy Technology Data Exchange (ETDEWEB)
Semmler, Renato
2006-07-01
Photoneutron cross sections measurements of {sup 9}Be, {sup 13}C and {sup 17}O have been obtained in the energy interval between 1,6 and 10,8 MeV, using neutron capture gamma-rays with high resolution in energy (3 a 21 eV), produced by 21 target materials, placed inside a tangential beam port, near the core of the IPEN/CNEN-SP IEA-R1 (5 MW) research reactor. The samples have been irradiated inside a 4{pi} geometry neutron detector system 'Long Counter', 520,5 cm away from the capture target. The capture gamma-ray flux was determined by means of the analysis of the gamma spectrum obtained by using a Ge(Li) solid-state detector (EG and G ORTEC, 25 cm{sup 3}, 5%), previously calibrated with capture gamma-rays from a standard target of Nitrogen (Melamine). The neutron photoproduction cross section has been measured for each target capture gamma-ray spectrum (compound cross section). A inversion matrix methodology to solve inversion problems for unfolding the set of experimental compound cross sections, was used in order to obtain the cross sections at specific excitation energy values (principal gamma line energies of the capture targets). The cross sections obtained at the energy values of the principal gamma lines were compared with experimental data reported by other authors, with have employed different gamma-ray sources. A good agreement was observed among the experimental data in this work with reported in the literature. (author)
Review and calculation of Mott scattering cross section by unscreened point nuclei
International Nuclear Information System (INIS)
Idoeta, R.; Legarda, F.
1992-01-01
A new tabulation of the ratio of the ''exact'' Mott cross section for unscreened point nuclei to the classical Rutherford cross section for electrons and positions has been made. Because of the infinite slowly converging series appearing in this ratio we have made two series transformations. With this evaluation the ratio reached convergence within six significant figures after less than a hundred terms and very low computing time. So the ratios evaluated have less relative error than those in the literature and covers a greater range of energy and atomic number. (orig.)
Approach synthesis of superheavy nuclei from some aspects of cross section calculations
International Nuclear Information System (INIS)
Liu Zuhua
2003-01-01
Several important aspects in the cross section calculations for the synthesis of superheavy nuclei have been inquired. They are the effects of the coupled-channels, the damping of shell correction energy, the collective enhancements in the level density and the spin distributions of evaporation residues. The channel coupling of relative motion with internal degrees of freedom will enhance significantly the capture cross section at sub-barrier energies. However, recent measurements of spin distributions for the survived compound nucleus show that only low partial waves contribute to the evaporation residues, which should at least partially cancel out the enhancement due to the effects of the channel coupling. The fission barriers are determined mainly by the shell correction energy in the case of superheavy nuclei. Therefore, it is especially important to determine as accurate as possible the damping parameter which describes the decrease of the shell effects influence. In addition, the collective enhancement factor in the level density also plays a very important role in the synthesis of heavy spherical nuclei
Neutron-induced cross sections of short-lived nuclei via the surrogate reaction method
Directory of Open Access Journals (Sweden)
Morel P.
2011-10-01
Full Text Available The measurement of neutron-induced cross sections of short-lived nuclei is extremely difficult due to the radioactivity of the samples. The surrogate reaction method is an indirect way of determining cross sections for nuclear reactions that proceed through a compound nucleus. This method presents the advantage that the target material can be stable or less radioactive than the material required for a neutron-induced measurement. We have successfully used the surrogate reaction method to extract neutron-induced fission cross sections of various short-lived actinides. In this work, we investigate whether this technique can be used to determine neutron-induced capture cross sections in the rare-earth region.
Neutron-induced cross sections of short-lived nuclei via the surrogate reaction method
Directory of Open Access Journals (Sweden)
Tassan-Got L.
2012-02-01
Full Text Available The measurement of neutron-induced cross sections of short-lived nuclei is extremely difficult due to the radioactivity of the samples. The surrogate reaction method is an indirect way of determining cross sections for nuclear reactions that proceed through a compound nucleus. This method presents the advantage that the target material can be stable or less radioactive than the material required for a neutron-induced measurement. We have successfully used the surrogate reaction method to extract neutron-induced fission cross sections of various short-lived actinides. In this work, we investigate whether this technique can be used to determine neutron-induced capture cross sections in the rare-earth region.
International Nuclear Information System (INIS)
Zheng Jiwen; Zhang Li; Zhao Jinhua; Hu Qingyuan
1999-01-01
A technique for abstracting independent cross section on the basis of the γ activities from the observed isotope itself or its successively decayed daughter nuclei was developed. It is specially applicable for determining the independent cross sections of the isotope products involved in quick, element-separated samples. The authors have used it in the isotope-distribution measurement for Hg element produced in the reaction of 600-MeV 18 O beam bombarding on thick natural lead target, and a total of Hg-isotope independent cross sections more than twenty were obtained in the mass range of 180∼209. Some representative examples showing how the authors deduced these independent cross sections are given
Band crossings in mercury nuclei: effect of occupation of i13/2 neutron orbits
International Nuclear Information System (INIS)
Khadkikar, S.B.; Praharaj, C.R.
1984-04-01
The K=0 + ground band and two rotation-aligned bands (K=1 + or K2 + two quasi-particle band and K=2 + four quasi-particle band) are studied in 198 Hg, 194 Hg and 190 Hg by angular momentum projection from Hartree-Fock and particle-hole intrinsic states. There is a first anomaly in these three nuclei around 8(h/2π) due to the crossing of the ground band and the two quasi-particle band. Because of the nature of occupation of i13/2 orbitals the four quasi-particle band is too highlying in 198 Hg and does not cross the two quasi-particle bands, while such a second crossing occurs in 194 Hg and 190 Hg near 20 (h/2π). (author)
Neutrino-induced neutral-current reaction cross sections for r-process nuclei
Langanke, K
2002-01-01
Neutrino-induced reactions play an important role during and after the r-process, if the latter occurs in an environment with extreme neutrino fluxes such as the neutrino-driven wind model or neutron star mergers. Recently we have evaluated the charged-current neutrino-nucleus cross sections relevant for r-process simulations. We extend our approach here to the neutral-current cross sections. Our tabulation considers neutron-rich nuclei with neutron numbers N=41-135 and charge numbers Z=21-82 and lists total as well as partial neutron spallation cross sections. The calculations have been performed within the random phase approximation considering multipole transitions with J<=3 and both parities. The supernova neutrino spectrum is described by a Fermi-Dirac distribution with various temperature parameters between T=2.8 MeV and T=10 MeV and with the degeneracy parameters alpha=0 and alpha=3.
Personnel hazards from medical electron accelerator photoneutrons
International Nuclear Information System (INIS)
Mcall, R.C.; Jenkins, T.M.; Shore, R.A.; LaRiviere, P.D.
1980-01-01
Medical electron accelerators operated in the photon mode produce significant amounts of photoneutrons at energies above 15 MeV. There can be definite radiation problems at doors of treatment rooms where operating consoles are often located. These problems are due in large part to inadequate maze design by physicists unaccustomed to shielding against neutrons. The radiation field at the door is an unusual combination of low energy neutrons, thermal neutrons and capture γ-rays from the concrete walls of the maze and the door itself. While this radiation field is dependent upon the actual construction details, these three components each contribute roughly one-third of the total dose equivalent. Reducing these high radiation levels presents a formidable problem. The neutrons can be absorbed by hydrogenous material which can be attached to the door, but the neutron capture γ-rays would require massive amounts of lead for the required attenuation. Both measurements and Monte Carlo calculations are presented to illustrate the problem. Some possible shielding solutions are presented for pre-existing treatment rooms, as well as design recommendations for new rooms. (H.K.)
Monitoring of MNSR operation by measuring subcritical photoneutron flux
International Nuclear Information System (INIS)
Haddad, Kh.; Alsomel, N.
2011-01-01
Passive nondestructive assay methods are used to monitor the reactor's operation. It is required for nuclear regulatory, calculation validation and safeguards purposes. So, it plays a vital role in the safety and security of the nuclear plants. The possibility of MNSR operation monitoring by measuring the subcritical state photoneutron flux were investigated in this work. The photoneutron flux is induced by the fuels hard gamma radiation in the beryllium reflector. Theoretical formulation and experimental tests were performed. The results show that within a specified cooling time range, the photoneutron flux is induced by a single dominant hard gamma emitter such as 117 Cd (activation product) and 140 Ba ( 140 La fission product). This phenomenon was utilized to monitor the cooling time and the operation neutron flux during the last campaign. Thus a passive nondestructive assay method is proposed with regard to the reactor operation's monitoring.
The simulation of resonance photoneutron produced by dragon-I
International Nuclear Information System (INIS)
Xiang Yanjun; Ma Jingfang
2010-01-01
The temperature measurement using neutron resonance spectroscopy has many advantages such as non-immerging, inside measurement and local temperature distribution measurement, but the deficiency of high intensity pulsed neutron source limits it's application.In order to study the feasibility of Dragon-I as the pulsed neutron source of temperature measurement, the photoneutron characteristic had been simulated by MCNP5, the photoneutron yield is 1.34 x 10 11 per electron pulse, pulse width is 90ns. the yield is as high as 7.47 x 10 12 per electron pulse when 8cm thick U target had been used, which is only one magnitude lower than the yield of spallation source. the moderation of photoneutron had been simulated using some moderator, the results displayed Dragon-I can be a high intensity,narrow pulse neutron source, it's necessary to study further about it's application to temperature measurement using neutron resonance spectroscopy. (authors)
Band crossing and signature splitting in odd mass fp shell nuclei
International Nuclear Information System (INIS)
Velazquez, Victor; Hirsch, Jorge G.; Sun, Yang
2001-01-01
Structure of two sets of mirror nuclei: 47 V- 47 Cr and 49 Cr- 49 Mn, as well as 49 V and 51 Mn, is studied using the projected shell model. Their yrast spectra are described as an interplay between the angular momentum projected states around the Fermi level which carry different intrinsic K-quantum numbers. The deviations from a regular rotational sequence are attributed to band crossing and signature splitting, which are usually discussed in heavy nuclear systems. Our results agree reasonably with experimental data, and are comparable with those from the full pf shell model calculations
Nohara, Kazunari; Chen, Zheng; Yoo, Seung-Hee
2017-07-06
Chromatin immunoprecipitation (ChIP) is a powerful method to determine protein binding to chromatin DNA. Fiber-rich skeletal muscle, however, has been a challenge for ChIP due to technical difficulty in isolation of high-quality nuclei with minimal contamination of myofibrils. Previous protocols have attempted to purify nuclei before cross-linking, which incurs the risk of altered DNA-protein interaction during the prolonged nuclei preparation process. In the current protocol, we first cross-linked the skeletal muscle tissue collected from mice, and the tissues were minced and sonicated. Since we found that ultracentrifugation was not able to separate nuclei from myofibrils using cross-linked muscle tissue, we devised a sequential filtration procedure to obtain high-quality nuclei devoid of significant myofibril contamination. We subsequently prepared chromatin by using an ultrasonicator, and ChIP assays with anti-BMAL1 antibody revealed robust circadian binding pattern of BMAL1 to target gene promoters. This filtration protocol constitutes an easily applicable method to isolate high-quality nuclei from cross-linked skeletal muscle tissue, allowing consistent sample processing for circadian and other time-sensitive studies. In combination with next-generation sequencing (NGS), our method can be deployed for various mechanistic and genomic studies focusing on skeletal muscle function.
International Nuclear Information System (INIS)
Savin, M.V.; Nefedov, Yu.Ya; Livke, A.V.; Zvenigorodskij, A.G.
2001-01-01
Experimental data on the total gamma-ray production cross-sections for inelastic interaction of fast neutrons with iron nuclei were analysed. The total gamma-ray production cross-sections, grouped according to E γ , were evaluated in the neutron energy range 0.5-19 MeV. The statistical spline approximation method was used to evaluate the experimental data. Evaluated data stored in the ENDF, JENDL, BROND, and other libraries on gamma-ray production spectra and cross-sections for inelastic interaction of fast neutrons with iron nuclei, were analysed. (author)
Energy Technology Data Exchange (ETDEWEB)
de Saussure, G.; Perez, R.B. (Oak Ridge National Lab., TN (USA))
1982-01-01
Several problems related to the measurement, analysis and evaluation of the neutron cross sections of the main fertile and fissile nuclides in the resonance region are reviewed. In particular the ENDF/B-V representation of these cross sections is discussed. In recent years little progress has been made in improving our knowledge of the resolved resonance parameters of the fertile nuclei. It is suggested that this absence of progress is due to a lack of adequate methodologies to deal with the systematic errors arising from uncertainties in the analysis of the measurements. The ENDF/B treatment of the unresolved resonance region is commented on and the authors recommend the validation of the unresolved resonance range evaluations with appropriate transmission and self-indication measurements.
International Nuclear Information System (INIS)
Kotov, Alexander; Chtchetkovski, Alexander; Fedorov, Oleg; Gavrikov, Yuri; Chestnov, Yuri; Poliakov, Vladimir; Vaishnene, Larissa; Vovchenko, Vil; Fukahori, Tokio
2003-01-01
The purpose of this work is experimental studies of the energy dependence of the fission cross sections of heavy nuclei, nat Pb, 209 Bi, 232 Th, 233 U, 235 U, 238 U, 237 Np and 239 Pu, by protons at the energies from 200 to 1000 MeV. At present experiment the method based on use of the gas parallel plate avalanche counters (PPACs) for registration of complementary fission fragments in coincidence and the telescope of scintillation counters for direct counting of the incident protons on the target has been used. First preliminary results of the energy dependences of proton induced fission cross sections for nat Pb, 209 Bi, 235 U and 238 U are reported. (author)
Microscopic theory of the total reaction cross section and application to stable and exotic nuclei
International Nuclear Information System (INIS)
Hussein, M.S.; Rego, R.A.; Bertulani, C.A.
1990-09-01
The multiple scattering theory is used to develop a theoretical framework for the calculation of the heavy-ion total reaction order double scattering contribution to the ion-ion t sub(ρ1 ρ2) interaction is calculated and found to contribute at most 10% effect on σ sub(R). It is found that whereas at intermediate energies the t sub(ρ1ρ2) accounts reasonably well for the total reaction cross section, indicating the predominance, at these energies, of single nucleon knockout, it underestimates σ sub(R) at lower energies by a large amount. This is mainly due to the absence in t sub(ρ1ρ2) of fusion and inelastic surface excitation. The case of exotic (neutron-and proton-rich) nuclei is also discussed. (author) the absence
Location of DNA-protein cross-links in mammalian cell nuclei
International Nuclear Information System (INIS)
Oleinick, N.L.
1985-01-01
DNA-protein cross-links (DPCs) occur in 1-3% of the bulk DNA of unirradiated cells, and dose-dependent increases in DPCs with γ- or UV-radiation can be detected by filter-binding. DPCs may contribute to cell lethality, since their formation is prevented by radical scavengers. Since the environment of DNA varies within eukaryotic nuclei, we have probed the composition and sub-nuclear location of DPCs. Both before and after irradiation, the major proteins cross-linked to DNA have molecular weights similar to known proteins of the nuclear matrix. The DNA cross-linked to protein is enriched in sequences which hybridize to mRNA or rRNA transcripts; such sequences are also found preferentially in preparations of nuclear matrix. When histone-depleted, matrix-associated DNA is separated from the DNA of the supercoiled ''loops'' by digestion with EcoRI and assayed for DPCs by filter binding, the frequency of DPCs is greater in the matrix. During repair of DPCs, protein-associated DNA becomes depleted in actively transcribing DNA, followed by reconstitution of the active-gene-enriched nuclear matrix. These data are consistent with known properties of the matrix and suggest the hypothesis that in intact cells, radiation-induced DPCs are primarily a product of matrix-associated DNA sequences and matrix protein
Reduction methodology for reaction cross sections induced by weakly bound nuclei
International Nuclear Information System (INIS)
Deshmukh, N.N.; Mukherjee, S.; Appannababu, S.; Guimaraees, V.; Lubian, J.; Gomes, P.R.S.
2009-01-01
The interest in nuclear reactions with weakly bound nuclei has increased considerably along the last decade. Several experiments with stable and unstable projectiles have been performed and a variety of theoretical approaches have been developed. In particular, fusion and breakup reactions induced by such projectiles have been the object of several studies. Owing to the weak binding of the projectile, the breakup cross section may be quite large and coupling with the breakup channel can strongly affect the fusion cross section at near barrier energies. This influence stems from two effects, one of a static and the other of a dynamic nature, which are, however, not easy to be disentangled. The static effect results from the more diffuse density of the weakly bound nuclei, as compared with a strongly bound one. The contribution from weakly bound nucleons to the nuclear density extends further out and this gives rise to a lower and thicker potential barrier. There is general understanding that this static effect enhances the fusion cross section at near barrier energies. On the other hand, there is the dynamic effect corresponding to the coupling with the breakup channel. It is well known that the coupling with a finite number of bound channels enhances the sub-barrier fusion cross section. However, the effect of coupling to channels in the continuum (breakup) is controversial. In first place, one should have in mind that there are different fusion processes in collisions of weakly bound projectiles. One of such processes is the complete fusion, which takes place when the whole mass of the projectile fuses with the target. There may be fusion following breakup. In this case, the compound nucleus may contain the whole mass of the projectile (through sequential fusion of the fragments), or some fragment can escape the interaction region. The former corresponds also to complete fusion (sequential complete fusion) while the latter is known as incomplete fusion. So far
NAA using the photoneutrons of a Linac as a neutron source
International Nuclear Information System (INIS)
Rivera P, E.; De Leon M, H. A.; Hernandez D, V. M.; Vega C, H. R.; Soto B, T.; Gallego, E.; Lorente, A.
2012-10-01
Linear accelerators working above 8 MV produce photoneutrons that represent a radiological risk in the patient and hospital staff. In this work a moderator has been designed in the aim to use the photoneutron field to perform neutron activation analysis (NAA) of small samples. The moderator has been designed using Monte Carlo methods, here the photoneutron spectrum is modified by the moderator having the maximum thermal neutron flux in the moderator cavity where the sample to be analyzed is located. (Author)
Total photoabsorption cross section on nuclei measured in energy range 0.5-2.6 GeV
International Nuclear Information System (INIS)
Mirazita, M.
1998-03-01
The total photoabsorption cross section on several nuclei has been measured in the energy range 0.5 - 2.6 GeV. Nuclear data show a significant reduction of the absorption strength with respect to the free nucleon case suggesting a shadowing effect at low energies
Differential cross section measurement of radiative capture of protons by nuclei 13C
International Nuclear Information System (INIS)
Baktibayev, M.K.; Burminskii, V.P.; Burtebayev, N.; Jazairov-Kakhramanov, V.; Kadyrzhanov, K.K.; Sagindykov, Sh.Sh.; Zarifov, R.A.; Zazulin, D.M.
2004-01-01
The reaction 13 C(p,γ ) 14 N is the important one for the astrophysics, not only for nuclear synthesis of CNO elements, but also for nuclear synthesis of elements participating in subsequent combustion of helium [1]. The predominant yield of the reaction occurs at protons energies of less than 1 MeV. However, the clearness of the capture mechanism in this energy region is made difficult because of the superposition of the contribution of the low - energy part of the resonance 1320 keV onto the cross section. Last experimental data for a wider energy region, informed in the work [1], and results of previous works, mentioned in that work, give reason for further continuation of the study of the reaction 13 C(p,γ ) 14 N. Measured data of the work [1] in the region of E P = (320 - 900) keV at the angles of 0 o and 90 o are obviously insufficient. In the present work measurements of differential cross sections of the reaction were carried out at protons energies E P = 991 - 365 keV, the accuracy is not worse than 10%. There was studied the most (from the astrophysical point of view) important process of protons capture by 13 C nuclei onto the ground state of the 14 N nucleus. The theoretical investigation of the given reaction included calculation of cross sections. The cross sections were calculated within the framework of model of direct capture with the using of optical potentials for the description of a channel of scattering. The wave functions of a bound state were generated in a potential reproducing binding energy of a proton in 14 N nucleus. Results of calculations were compared with the experimental data. (author)
Evaluation of the (n,xn) and (n,xnf) cross sections for heavy nuclei with the statistical model
International Nuclear Information System (INIS)
Jary, J.
1975-01-01
A method was presented to calculate the (n,xn) and (n,xnf) cross sections for the heavy nuclei having mass numbers of 232 1) without fission, according to the law of conventional statistical models, in the (n,xn) process. Fission can also compete with the emission of neutrons and γ-ray for the nuclei and the excitation energy considered. The fission cross sections of 235 U and 238 U recently evaluated by Sowerby and the fission cross section of 236 U have been used to determine the other parameters needed in the calculation. The fission widths of 239 U and 238 U have been obtained by fitting the first-chance and second-chance fission plateaus of the 238 U cross section. For the fission width of 238 U, good agreement was observed between the authors' results and Landrum and others' experimental data. (Iwase, T.)
Delayed photoneutrons of the of the Dalat Nuclear Research Reactor
International Nuclear Information System (INIS)
Ngo Quang Huy; Ha Van Thong; Vu Hai Long; Ngo Phu Khang; Nguyen Nhi Dien; Pham Van Lam; Huynh Dong Phuong; Luong Ba Vien; Le Vinh Vinh
1994-01-01
Time spectrum of delayed neutrons of the Dalat nuclear research reactor is measured and analyzed. It corresponds to a shut-down neutron fluxes of about 10 5 /10 8 n/cm 2 /sec after 100 hours continuous reactor operation at steady power level of 500 kW. Data processing of experimental time neutron spectrum gives 16 exponents, of which 10, resulting from photoneutrons due to (γ,n) reactions on beryllium used inside the reactor core, are obtained by using successive exponential stripping fitting method. For the Dalat reactor, the effective delayed photoneutron fraction relative to the total effective delayed neutron fraction is β B e eff =0.49%β eff for a beryllium weight relative to U 235 fuel of m B e/m U = 8.5. This result is acceptable in comparison to those obtained for other Be-U 235 media. (author). 5 refs., 2 figs., 4 tabs
Photons and photoneutrons spectra of a Linac of 15 MV
International Nuclear Information System (INIS)
Benites R, J. L.; Carrillo C, A.; Vega C, H. R.; Velazquez F, J. B.
2011-10-01
Using the Monte Carlo code MCNP-5, the photons and photoneutrons spectra generated in the head stock of the lineal accelerator (Linac) Varian of 15 MV of the Cancerology State of Nayarit were determined. For the calculations a heterogeneous head stock was modeled, more compatible with the work conditions. In the center of the head stock a tungsten target was located on a copper support, followed by the flattened filter. The photons and photoneutrons spectra were obtained accelerating electrons and making them collide against the target to produce photons by Bremsstrahlung, these photons were transported inside the head stock and the photons and photoneutrons spectra were calculated in a punctual detector located under the flattened filter and in the isocenter. The spectra were evaluated in punctual detectors that were located in the plane from the isocenter to the long of the X and Y axes each 20 cm, in an equidistant way, up to 2 m, so much in the longitudinal and transversal axes. In the calculations were used histories 5E(6) with the purpose of obtaining smaller uncertainties to 1%. It was found that the photons spectrum in the punctual detector inside the head stock presents a pick of 1.25 MeV in the energy interval of 0.5 and 1.5 MeV, later suffers a filtration and diminishes in asymptote form. This spectrum modifies when the beam reaches the isocenter, diminishing the low energy photons. Inside the head stock the photoneutrons spectrum shows a structure with two picks, one before 1 MeV and other after 1 MeV; this is for effect of the collimators geometry and the distance. Finally an increment of the total neutrons flow to 60 cm of distance of the isocenter on the Y axis was observed, due to the design geometry of the modeling heterogeneous head stock. (Author)
Energy Technology Data Exchange (ETDEWEB)
Tatari, Mansoureh [Yazd Univ. (Iran, Islamic Republic of). Physics Dept.; Naik, Haladhara [Bhabha Atomic Research Centre, Mumbai (India). Radiochemistry Div.; Kim, Guinyun; Kim, Kwangsoo [Kyungpook National Univ., Daegu (Korea, Republic of). Dept. of Physics; Shin, Sung-Gyun; Cho, Moo-Hyun [Pohang Univ. of Science and Technology (Korea, Republic of). Div. of Advanced Nuclear Engineering
2017-07-01
The flux-weighted average cross sections of the {sup 89}Y(γ,xn; x=1-4){sup 89-x}Y reactions and the isomeric yield ratios of the {sup 87m,g}Y, {sup 86m,g}Y, and {sup 85m,g}Y radionuclides produced in these reactions with the bremsstrahlung end-point energies of 65, 70 and 75 MeV have been determined by an activation and off-line γ-ray spectrometric technique using the 100 MeV electron linac in Pohang Accelerator Laboratory, Korea. The theoretical {sup 89}Y(γ,xn; x=1-4){sup 89-x}Y reaction cross sections for mono-energetic photons have been calculated using the computer code TALYS 1.6. Then the flux-weighted theoretical values were obtained to compare with the present data. The flux-weighted experimental and theoretical {sup 89}Y(γ,xn; x=1-4){sup 89-x}Y reaction cross sections increase very fast from the threshold values to a certain bremsstrahlung energy, where the other reaction channels open up. Thereafter it remains constant a while and then slowly decreases with the increase of cross sections for other reactions. Similarly, the isomeric yield ratios of {sup 87m,g}Y, {sup 86m,g}Y and {sup 85m,g}Y in the {sup 89}Y(γ,xn; x=2-4){sup 89-x}Y reactions from the present work and literature data show an increasing trend from their respective threshold values to a certain bremsstrahlung energy. After a certain point of energy, the isomeric yield ratios increase slowly with the bremsstrahlung energy. These observations indicate the role of excitation energy and its partitioning in different reaction channels.
Yamazaki, T.; Katayama, I.; Uwamino, Y.
1993-02-01
The possibility of a crossed beam facility of slow neutrons capturing unstable nuclei is examined in connection with the Japanese Hadron Project. With a pulsed proton beam of 50 Hz repetition and with a 100 μA average beam current, one obtains a spallation neutron source of 2.4 × 10 8 thermal neutrons/cm 3/spill over a 60 cm length with a 3 ms average duration time by using a D 2O moderator. By confining radioactive nuclei of 10 9 ions in a beam circulation ring of 0.3 MHz revolution frequency, so that nuclei pass through the neutron source, one obtains a collision luminosity of 3.9 × 10 24/cm 2/s. A new research domain aimed at studying rapid processes in nuclear genetics in a laboratory will be created.
Hue, B. M.; Isataev, T.; Erdemchimeg, B.; Artukh, A. G.; Aznabaev, D.; Davaa, S.; Klygin, S. A.; Kononenko, G. A.; Khuukhenkhuu, G.; Kuterbekov, K.; Lukyanov, S. M.; Mikhailova, T. I.; Maslov, V. A.; Mendibaev, K.; Sereda, Yu M.; Penionzhkevich, Yu E.; Vorontsov, A. N.
2017-12-01
Preliminary results of measurements of the total reaction cross sections σR and neutron removal cross section σ-xn for weakly bound 6He, 8Li, 9Be and 10Be nuclei at energy range (20-35) A MeV with 28Si target is presented. The secondary beams of light nuclei were produced by bombardment of the 22Ne (35 A MeV) primary beam on Be target and separated by COMBAS fragment-separator. In dispersive focal plane a horizontal slit defined the momentum acceptance as 1% and a wedge degrader of 200 μm Al was installed. The Bρ of the second section of the fragment-separator was adjusted for measurements in energy range (20-35) A MeV. Two-neutron removal cross sections for 6He and 10Be and one -neutron removal cross sections 8Li and 9Be were measured.
Optimization studies of photo-neutron production in high-Z metallic ...
Indian Academy of Sciences (India)
Monte Carlo calculations have been performed using MCNP code to study the optimization of photo-neutron yield for different electron beam energies impinging on Pb, W and Ta cylindrical targets of varying thickness. It is noticed that photo-neutron yield can be increased for electron beam energies ≥ 100 MeV for ...
Differential cross section measurement of radiative capture of protons by nuclei 13C
International Nuclear Information System (INIS)
Baktibayev, M.K.; Burminskii, V.P.; Burtebayev, N.; Dzazairov-Kakhramanov, V.; Kadyrzhanov, K.K.; Sagindykov, Sh.Sh.; Zarifov, R.A.; Zazulin, D.M.
2004-01-01
Full text: The reaction 13 C(p,γ ) 14 N is the important one for the astrophysics, not only for nuclear synthesis of CNO elements, but and for nuclear synthesis of elements participating in subsequent combustion of helium [1]. The predominant yield of the reaction occurs at protons energies of less than 1 MeV. However, the clearness of the capture mechanism in this energy region is made difficult because of the superposition of the contribution of the low - energetical part of the resonance 1320 keV onto the cross section. Last experimental data for more wide energy region, informed in the work [1], and results of previous works, mentioned in that work, give reason for further continuation of the study of the reaction 13 C(p,γ ) 14 N. Measured data of the work [1] in the region of E ρ = (320 † 900) keV at the angles of 0 o and 90 o are obviously insufficient. In the present work measurements of differential cross sections of the reaction were carried out at protons energies E p = 991, 558 and 365 keV, the accuracy is not worse then 10%. There was studied the most (from the astrophysical point of view) important process of protons capture by 13 C nuclei onto the ground state of the 14 N nucleus. The 13 C (99%) targets, used in the experiment, were sprayed onto copper base. The target thickness was determined by incident protons energy losses in the target. The energy losses were clearly reflected in the corresponding spreading of transitions of radiation capture. The statement about the gamma-lines spreading is valid in this case, because energy losses in the target are here significantly more, than the energetical resolution of the detector. The peak width of the radiation capture gamma-line at half-height corresponds to energy losses of incident protons in the target. From the Table of brake values for protons in carbon [2] there was determined that the thickness of the target was 140 ± 5% μg/cm 2 . The upper part of gamma-lines in the spectrum repeats the
International Nuclear Information System (INIS)
Grudzevich, O.D.; Zelenetskij, A.V.; Pashchenko, A.B.
1986-01-01
The last version of the KOP program for calculating cross sections of neutron and charged particle interaction with atomic nuclei within the scope of the optical model is described. The structure and program organization, library of total parameters of the optical potential, program identificators and peculiarities of its operation, input of source data and output of calculational results for printing are described in detail. The KOP program is described in Fortran- and adapted for EC-1033 computer
Energy Technology Data Exchange (ETDEWEB)
Anne, R [CEA Centre d' Etudes Nucleaires de Saclay, 91 - Gif-sur-Yvette (France). Service d' Entretien et de Developpement des Appareils de Physique; Delpierre, P; Kahane, J; Sene, R [College de France, 75 - Paris. Lab. de Physique Corpusculaire; Devaux, A; Landaud, G [Clermont-Ferrand Univ., 63 (France); Yonnet, J [Caen Univ., 14 (France). Lab. de Physique Corpusculaire
1975-01-01
Alpha knock out from light and medium nuclei up to /sup 40/Ca was investigated. Preliminary values of the differential cross sections are given for /sup 6/Li and /sup 12/C nuclei. The p(R) recoil momentum distributions show a maximum at p(R)=0.
Photoneutron spectrum measured with Bonner Spheres in Planetary method mode
Energy Technology Data Exchange (ETDEWEB)
Benites R, J. [Centro Estatal de Cancerologia de Nayarit, Servicio de Seguridad Radiologica, Calz. de la Cruz 118 Sur, 63000 Tepic, Nayarit (Mexico); Vega C, H. R. [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Apdo. Postal 336, 98000 Zacatecas (Mexico); Velazquez F, J., E-mail: jlbenitesr@prodigy.net.mx [Universidad Autonoma de Nayarit, Posgrado en Ciencias Biologico Agropecuarias, Carretera Tepic-Compostela Km 9, 63780 Jalisco-Nayarit (Mexico)
2012-10-15
We measured the spectrum of photoneutrons at 100 cm isocenter linear accelerator (Linac) Varian ix operating at 15 MV Bremsstrahlung mode. In this process was used a radiation field of 20 x 20 cm{sup 2} at a depth of 5 cm in a solid water phantom with dimensions of 30 x 30 x 15 cm{sup 3}. The measurement was performed with a system using it Bonner Spheres spectrometric method Planetary mode. As neutron detector of the spectrometer is used thermoluminescent dosimeters pairs of type 600 and 700. (Author)
Photoneutron spectrum measured with Bonner Spheres in Planetary method mode
International Nuclear Information System (INIS)
Benites R, J.; Vega C, H. R.; Velazquez F, J.
2012-10-01
We measured the spectrum of photoneutrons at 100 cm isocenter linear accelerator (Linac) Varian ix operating at 15 MV Bremsstrahlung mode. In this process was used a radiation field of 20 x 20 cm 2 at a depth of 5 cm in a solid water phantom with dimensions of 30 x 30 x 15 cm 3 . The measurement was performed with a system using it Bonner Spheres spectrometric method Planetary mode. As neutron detector of the spectrometer is used thermoluminescent dosimeters pairs of type 600 and 700. (Author)
International Nuclear Information System (INIS)
Ghiasi, Hosein; Mesbahi, Asghar
2012-01-01
The effect of wall material on photoneutron production in radiation therapy rooms was studied using Monte Carlo (MC) simulations. An analytical formula was proposed to take into account the concrete composition in photoneutron dose calculations. Using the MCNPX MC code, the 18 MV photon beam of the Varian Clinac 2100 and a typical treatment room with concrete compositions according to report No. 144 of National Council of Radiation Protection (NCRP) were simulated. Number of room produced photoneutrons per Gray of X-ray at the isocenter was determined for different types of concrete and named as “Q W ”. This new factor was inserted in the used formula for photoneutron fluence calculations at the inner entrance of maze. The photoneutron fluence was calculated using new proposed formula at the inner entrance of maze for all studied concretes. The difference between conventional and proposed equations varied from 11% to 46% for studied concretes. It was found that room produced photoneutrons could be significant for high density concretes. Additionally, applying the new proposed formula can consider the effect of wall material composition on the photoneutron production in high energy radiation therapy rooms. Further studies to confirm the accuracy of newly developed method is recommended.
Grosse, Eckart; Massarczyk, Ralph
2014-01-01
Cross sections for neutron capture in the range of unresolved resonances are predicted simultaneously to level distances at the neutron threshold for more than 100 spin-0 target nuclei with A >70. Assuming triaxiality in nearly all these nuclei a combined parameterization for both, level density and photon strength is presented. The strength functions used are based on a global fit to IVGDR shapes by the sum of three Lorentzians adding up to the TRK sum rule and theory-based predictions for the A-dependence of pole energies and spreading widths. For the small spins reached by capture level densities are well described by only one free global parameter; a significant collective enhancement due to the deviation from axial symmetry is observed. Reliable predictions for compound nuclear reactions also outside the valley of stability as expected from the derived global parameterization are important for nuclear astrophysics and for the transmutation of nuclear waste.
Energy Technology Data Exchange (ETDEWEB)
Back, B.B.; Blumenthal, D.J.; Davids, C.N. [and others
1995-08-01
The fission hindrance of hot nuclei was deduced recently from an enhanced emission of GDR {gamma} rays, neutrons and charged particles prior to scission of heavy nuclei. In the most recent experiments addressing this topic, namely new measurements of the pre-scission {gamma} rays and evaporation residues from the {sup 32}S + {sup 184}W reaction, a rather sharp transition from negligible to full one-body dissipation occurs over the excitation energy region E{sub exc} = 60-100 MeV. However, the cross section does not appear to level out or start to decline again at the upper end of the energy range as expected in this interpretation. It is therefore clearly desirable to extend the excitation energy range to look for such an effect in order to either corroborate or refute this interpretation.
International Nuclear Information System (INIS)
Nilsen, B.S.; Waddington, C.J.; Cummings, J.R.; Garrard, T.L.; Klarmann, J.
1995-01-01
With the addition of krypton and silver projectiles we have extended our previous studies of the fragmentation of heavy relativistic nuclei in targets ranging in mass from hydrogen to lead. These projectiles were studied at a number of discrete energies between 450 and 1500A MeV. The total and partial charge-changing cross sections were determined for each energy, target, and projectile, and the values compared with previous predictions. A new parametrization of the dependence of the total charge-changing cross sections on the target and projectile is introduced, based on nuclear charge radii derived from electron scattering. We have also parametrized the energy dependence of the total cross sections over the range of energies studied. New parameters were found for a previous representation of the partial charge-changing cross sections in hydrogen and a new parametrization has been introduced for the nonhydrogen targets. The evidence that limiting fragmentation has been attained for these relatively light projectile nuclei at Bevalac energies is shown to be inconclusive, and further measurements at higher energies will be needed to address this question
Energy Technology Data Exchange (ETDEWEB)
Auclair, J M; Hubert, P; Joly, R; Vendryes, G; Jacrot, B; Netter, F [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires; Galula, M [Centre National de la Recherche Scientifique (CNRS), 91 - Gif-sur-Yvette (France)
1955-07-01
It presents the experimental measurements of cross section of fissile nuclei for slow neutrons to improve the understanding of some heavy nuclei of great importance in the study of nuclear reactors. The different experiments are divided in three categories. In the first part, it studied the variation with energy of the cross sections of natural uranium, {sup 233}U, {sup 235}U and {sup 239}Pu. Two measurement techniques are used: the time-of-flight spectrometer and the crystal spectrometer. In a second part, the fission cross sections of {sup 233}U and {sup 239}Pu for thermal neutrons are compared using a neutron flux from EL-2 going through a double fission chamber. The matter quantity contained in each source is measured by counting the {alpha} activity with a solid angle counter. Finally, the average cross section of {sup 236}U for a spectra of neutrons from the reactor is measured by studying the {beta} activity of {sup 237}U formed by the reaction {sup 236}U (n, {gamma}) {sup 237}U in a sample of {sup 236}U irradiated in the Saclay reactor (EL-2). (M.P.)
Delayed photoneutrons of the of the Dalat Nuclear Research Reactor
Energy Technology Data Exchange (ETDEWEB)
Huy, Ngo Quang [Centre for Nuclear Technique Application, Ho Chi Minh City (Viet Nam); Thong, Ha Van; Long, Vu Hai; Khang, Ngo Phu; Dien, Nguyen Nhi; Lam, Pham Van; Phuong, Huynh Dong; Vien, Luong Ba; Vinh, Le Vinh [Nuclear Research Inst., Da Lat (Viet Nam)
1994-10-01
Time spectrum of delayed neutrons of the Dalat nuclear research reactor is measured and analyzed. It corresponds to a shut-down neutron fluxes of about 10{sup 5}/10{sup 8} n/cm{sup 2}/sec after 100 hours continuous reactor operation at steady power level of 500 kW. Data processing of experimental time neutron spectrum gives 16 exponents, of which 10, resulting from photoneutrons due to ({gamma},n) reactions on beryllium used inside the reactor core, are obtained by using successive exponential stripping fitting method. For the Dalat reactor, the effective delayed photoneutron fraction relative to the total effective delayed neutron fraction is {beta}{sup B}e{sub eff}=0.49%{beta}{sub eff} for a beryllium weight relative to U{sup 235} fuel of m{sub B}e/m{sub U} = 8.5. This result is acceptable in comparison to those obtained for other Be-U{sup 235} media. (author). 5 refs., 2 figs., 4 tabs.
International Nuclear Information System (INIS)
Iwasaki, Shin
1984-01-01
Measurements of double differential cross sections (DDX) for several intermediate and heavy nuclei have been performed at 15 MeV in the Dynamitron Laboratory at Tohoku University. Comparison of the experimental data with the evaluated nuclear data file, ENDF/B-IV revealed that the data file could not reproduce the experimental ones, particularly in the angular distributions. Nuclear model calculation showed that the preequilibrium process was important in the present incident energy region. Measurements have been performed for titanium, niobium, molybdenum, lead, and thorium (in progress), including the light elements, carbon and aluminum. (author)
Coherent production on nuclei and measurements of total cross sections for unstable particles
International Nuclear Information System (INIS)
Czyz, W.; Zielinski, M.
1980-01-01
The Koelbig-Margolis Formula is fitted to some explicity nonperturbative models of diffractive production. It is shown that, in spite of the fact that the standard procedure of fitting the integrated cross sections may give acceptable fits, thus obtained ''cross sections of unstable particles'', grossly disagree with the ''true'' cross sections known exactly from the models. (author)
International Nuclear Information System (INIS)
Varlamov, V.V.; Efimkin, N.G.; Ishkhanov, B.S.; Sapunenko, V.V.
1994-12-01
The authors describe a method based on the reduction method for the evaluation of photonuclear reaction cross-sections obtained under conditions where there are large systematic uncertainties (different instrumental functions, calibration and normalization errors). The evaluation method involves using the actual instrumental function (photon spectrum) of each individual experiment to reduce the data to a representation generated by an instrumental function of better quality. The objective is to find the most reasonably achievable monoenergetic representation of the information on the reaction cross-section derived from the results of various experiments and to take into account the calibration and normalization errors in these experiments. The method was used to obtain the evaluated total photoneutron reaction cross-section (γ,xn) for a large number of nuclei. Data obtained for 16 O and 208 Pb are presented. (author). 36 refs, 6 figs, 4 tabs
Reaction and total cross sections for low energy π+ and π- on isospin zero nuclei
International Nuclear Information System (INIS)
Saunders, A.; Ho/ibraten, S.; Kraushaar, J.J.; Kriss, B.J.; Peterson, R.J.; Ristinen, R.A.; Brack, J.T.; Hofman, G.; Gibson, E.F.; Morris, C.L.
1996-01-01
Reaction and total cross sections for π + and π - on targets of 2 H, 6 Li, C, Al, Si, S, and Ca have been measured for beam energies from 42 to 65 MeV. The cross sections are proportional to the target mass at 50 MeV, consistent with transparency to these projectiles. The cross sections are compared to theoretical calculations. copyright 1996 The American Physical Society
Energy Technology Data Exchange (ETDEWEB)
Escher, J. E. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
2017-04-11
Calculations for total cross sections and compound-nucleus (CN) formation cross sections for americium isotopes are described, for use in the 2017 NA-22 evaluation effort. The code ECIS 2006 was used in conjunction with Frank Dietrich's wrapper `runtemplate'.
Analysis of (n,2n) cross-section measurements for nuclei up to mass 238
International Nuclear Information System (INIS)
Davey, W.G.; Goin, R.W.; Ross, J.R.
1975-06-01
All suitable measurements of the energy dependence of (n,2n) cross sections of all isotopes up to mass 238 have been analyzed. The objectives were to display the quality of the measured data for each isotope and to examine the systematic dependence of the (n,2n) cross section upon N, Z, and A. Graphs and tables are presented of the ratio of the asymptotic (n,2n) and nonelastic cross section to the neutron-asymmetry parameter (N--Z)/A. Similar data are presented for the derived nuclear temperature, T, and level-density parameter, α, as a function of N, Z, and A. This analysis of the results of over 145 experiments on 61 isotopes is essentially a complete review of the current status of (n,2n) cross-section measurements
Measurement of cross sections producing short-lived nuclei by 14 MeV neutron. Br, Te, Dy, Ho, Yb
Energy Technology Data Exchange (ETDEWEB)
Sakane, H.; Matsumoto, T.; Yamamoto, H.; Kawade, K. [Nagoya Univ. (Japan); Iida, T.; Takahashi, A.
1997-03-01
Nine neutron activation cross sections producing the nuclei with half-lives between 2 min and 57 min have been measured at energy range between 13.4 and 14.9 MeV for Br, Te, Dy, Ho, Yb. The cross sections of {sup 81}Br(n,p){sup 81m}Se, {sup 128}Te(n,p){sup 128m}Sb, {sup 128}Te(n,{alpha}){sup 125m}Sn, {sup 164}Dy(n,p){sup 164}Tb, {sup 165}Ho(n,{alpha}){sup 162}Tb, {sup 176}Yb(n,p){sup 176}Tm were newly obtained at the six energy points between 13.4-14.9 MeV, although the previous results have been obtained at one energy point. {sup 79}Br(n,2n){sup 78}Br, {sup 164}Dy(n,p){sup 164}Tb are compared with evaluated data of JENDL-3.2. The evaluations for these reactions agree reasonably well with experimental results. The cross sections of (n,p) reaction are compared with systematics by Kasugai et. al. The systematics agrees with experimental results. (author)
Kawade, K; Kasugai, Y; Shibata, M; Iida, T; Takahashi, A; Fukahori, T
2003-01-01
We describe a method for obtaining reliable activation cross-sections in the neutron energy range between 13.4 and 14.9 MeV for the reactions producing short-lived nuclei with half-lives between 0.5 and 30 min. We noted neutron irradiation fields and measured induced activities, including (1) the contribution of scattered low-energy neutrons, (2) the fluctuation of the neutron fluence rate during the irradiation, (3) the true coincidence sum effect, (4) the random coincidence sum effect, (5) the deviation in the measuring position due to finite sample thickness, (6) the self-absorption of the gamma-ray in the sample material and (7) the interference reactions producing the same radionuclides or the ones emitting the gamma-ray with the same energy of interest. The cross-sections can be obtained within a total error of 3.6%, when good counting statistics are achieved, including an error of 3.0% for the standard cross-section of sup 2 sup 7 Al (n, alpha) sup 2 sup 4 Na. We propose here simple methods for measuri...
Energy Technology Data Exchange (ETDEWEB)
Schuhl, C [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires
1962-07-01
The absolute values of photoneutrons production cross-sections for the case of intermediate and heavy nuclei (lanthanium, cerium, tantalum, gold, lead and bismuth) are determined with an error of 15 per cent. The results obtained agree with theories in which the giant resonance is explained by the collective motion of the protons against the neutrons. The effect of the nuclear deformation on the shape of the giant resonance is seen in the case of Ta{sup 181}, it will be possible to determine the quadrupole momenta of deformed nuclei with a good accuracy when we shall increase the statistics of measurements. (author) [French] Les sections efficaces de production de photoneutrons par divers noyaux moyens et lourds (lanthane, cerium, tantale, or, plomb et bismuth) sont determinees en valeur absolue avec une erreur relative de 15 pour cent. Les resultats obtenus s'accordent avec les theories qui interpretent la resonance geante par un mouvement collectif des protons par rapport aux neutrons. L'influence de la deformation du noyau sur la forme de la resonance geante est soulignee dans le cas de {sup 181}Ta pour lequel elle se decompose en deux pics. Une amelioration de la statistique des mesures permettra de determiner les moments quadrupolaires des noyaux deformes avec une meilleure precision. (auteur)
Differential cross section measurement of radiative capture of protons by nuclei 12C
International Nuclear Information System (INIS)
Burtebayev, N.; Zazulin, D.M.; Buminskii, V.P.; Zarifov, R.A.; Tohtarov, R.N.; Sagindykov, Sh.Sh.; Baktibayev, M.K.
2003-01-01
Measurements of differential cross sections of nuclear reaction 12 C(p, γ) 13 N at 0, 45, 90, 135 Deg. to beam direction of flying protons in the field of E p = 350-1100 KeV with an error it is not worse than 10 % have been carried out. Most important was studied, from the astrophysical point of view, process of capture of protons by nucleuses 12 C on the ground state of a nucleus 13 N. It is experimentally shown isotropy of angular distribution of differential cross sections of reaction 12 C(p, γ) 13 N, in the given field energy of protons
Energy Technology Data Exchange (ETDEWEB)
Sanami, Toshiya; Baba, Mamoru; Saito, Keiichiro; Ibara, Yasutaka; Yamazaki, Tetsuro; Sato, Jun; Hirakawa, Naohiro [Tohoku Univ., Sendai (Japan)
1998-03-01
We have developed a measuring method of (n, {alpha}) cross section by using gaseous sample in a gridded ionization chamber. In this study, we measured the {sup 12}C(n, {alpha}{sub 0}) and the {sup 16}O(n, {alpha}{sub 0}), (n, {alpha}{sub 123}) cross sections for En=11.5 and 12.8 MeV neutrons. We also deduced the {sup 12}C(n, x{alpha}) spectrum and analyzed the data by a kinematic calculation combined with the reaction data of the {sup 12}C(n, n`3{alpha}). (author)
International Nuclear Information System (INIS)
Brenner, D.J.
1984-01-01
A model has been developed for calculating fast neutron cross sections (E > 14 MeV) for light nuclei of biomedical interest. The model explicitly includes experimental nuclear structure information. Some calculations for 12 C, 14 N, and 16 O are presented
International Nuclear Information System (INIS)
PIGNI, M.T.; HERMAN, M.; OBLOZINSKY, P.
2008-01-01
We produced a large set of neutron cross section covariances in the energy range of 5 keV-20 MeV. The present set of data on 57 structural materials and 31 heavy nuclei follows our earlier work on 219 fission product materials and completes our extensive contribution to the low-fidelity covariance project (307 materials). This project aims to provide initial, low-fidelity yet consistent estimates of covariance data for nuclear criticality safety applications. The evaluation methodology combines the nuclear reaction model code EMPIRE which calculates sensitivity to nuclear reaction model parameters, and the Bayesian code KALMAN that propagates uncertainties of the model parameters to cross sections. Taking into account the large scale of the project, only marginal reference to experimental data was made. The covariances were derived from the perturbation of several key model parameters selected by the sensitivity analysis. These parameters refer to the optical model potential, the level densities and the strength of the pre-equilibrium emission. This work represents the first attempt ever to generate nuclear data covariances on such a large scale
Experimental cross sections for the pickup of electrons by relativistic nuclei
International Nuclear Information System (INIS)
Raisbeck, G.M.; Crawford, H.J.; Lindstroem, P.J.; Greiner, D.E.; Beiser, F.S.; Heckman, H.H.
1977-01-01
Cross sections for the pickup of electrons in a variety of targets have been measured with beams of 12 C (150, 250, 400 MeV/n), 20 Ne (250, 400, 1050, 2100 MeV/n) and 40 Ar (400, 1050 MeV/n) from the Bevalac accelerator. The interpretation of the results in terms of radiative and non-radiative capture, and the implications for cosmic ray propagation studies are discussed. (author)
Directory of Open Access Journals (Sweden)
Banu Adriana
2018-01-01
Full Text Available The photodisintegration reaction cross-sections for 94Mo(γ,n and 90Zr(γ,n have been experimentally investigated with quasi-monochromatic photon beams at the High Intensity γ-Ray Source (HIγS facility, Triangle University Nuclear Laboratory (TUNL. The measurements were focused primarily on studying the energy dependence of the photoneutron cross sections, which is the most direct way of testing statistical models, and were performed close to the respective neutron thresholds and above up to ~ 20 MeV. Neutrons from the (γ,n reactions were detected using a 4π assembly of 3He proportional counters developed at Los Alamos National Laboratory and presently available at TUNL. While the 94Mo(γ,n cross section measurement aims to contribute to a broader investigation for understanding the γ-process (the mechanism responsible for the nucleosynthesis of the so-called p-nuclei, the information from the 90Zr(γ,n data is relevant to constrain QRPA calculations of γ-ray strength functions in this mass region. In this contribution, we will present our preliminary results of the total (γ,n excitation functions for the two photoneutron reactions on 94Mo and 90Zr.
Banu, Adriana; Silano, Jack; Karwowski, Hugon; Meekins, Evan; Bhike, Megha; Tornow, Werner; McCleskey, Mathew
2018-05-01
The photodisintegration reaction cross-sections for 94Mo(γ,n) and 90Zr(γ,n) have been experimentally investigated with quasi-monochromatic photon beams at the High Intensity γ-Ray Source (HIγS) facility, Triangle University Nuclear Laboratory (TUNL). The measurements were focused primarily on studying the energy dependence of the photoneutron cross sections, which is the most direct way of testing statistical models, and were performed close to the respective neutron thresholds and above up to 20 MeV. Neutrons from the (γ,n) reactions were detected using a 4π assembly of 3He proportional counters developed at Los Alamos National Laboratory and presently available at TUNL. While the 94Mo(γ,n) cross section measurement aims to contribute to a broader investigation for understanding the γ-process (the mechanism responsible for the nucleosynthesis of the so-called p-nuclei), the information from the 90Zr(γ,n) data is relevant to constrain QRPA calculations of γ-ray strength functions in this mass region. In this contribution, we will present our preliminary results of the total (γ,n) excitation functions for the two photoneutron reactions on 94Mo and 90Zr.
International Nuclear Information System (INIS)
Terranova, M.L.; Tavares, O.A.P.
1993-01-01
An analysis of the total photoabsorption cross section for nuclei ranging from 4 He up to 238 U has been performed in the energy range 0.2-1.0 GeV. Mean total photoabsorption cross sections have been obtained by summing up the contributions from partial photo reactions, and found to follow an A l -dependence in the 0.2-1.0 GeV range. A review of the available total photoabsorption cross section data is also presented. Comparisons have been made with cross section values calculated by considering both the quasi-deuteron and π-meson photoproduction mechanism of primary nuclear photo interaction. (author)
International Nuclear Information System (INIS)
Terranova, M.L.; Tavares, O.A.P.
1994-01-01
An analysis of the total photoabsorption cross section for nuclei ranging from 4 He up to 238 U has been performed in the energy range 0.2-1.0 GeV. Mean total photoabsorption cross sections have been obtained by summing up the contributions from partial photoreactions, and found to follow an A 1 -dependence in the 0.2-1.0 GeV range. A review of the available total photoabsorption cross section data is also presented. Comparisons have been made with cross section values calculated by considering both the quasi-deuteron and π-meson photoproduction mechanism of primary nuclear photointeraction. (orig.)
A theory of jet shapes and cross sections: from hadrons to nuclei
Energy Technology Data Exchange (ETDEWEB)
Vitev, Ivan [Los Alamos National Laboratory; Zhang, Benwei [Los Alamos National Laboratory; Wicks, Smon [COLUMBIA
2008-01-01
For jets, with great power comes great opportunity. The unprecedented center of mass energies available at the LHC open new windows on the QGP: we demonstrate that jet shape and jet cross section measurements become feasible as a new, differential and accurate test of the underlying QCD theory. We present a first step in understanding these shapes and cross sections in heavy ion reactions. Our approach allows for detailed simulations of the experimental acceptance/cuts that help isolate jets in such high-multiplicity environment. It is demonstrated for the first time that the pattern of stimulated gluon emission can be correlated with a variable quenching of the jet rates and provide an approximately model-independent approach to determining the characteristics of the medium-induced bremsstrahlung spectrum. Surprisingly, in realistic simulations of parton propagation through the QGP we find a minimal increase in the mean jet radius even for large jet attenuation. Jet broadening is manifest in the tails of the energy distribution away from the jet axis and its quantification requires high statistics measurements that will be possible at the LHC.
International Nuclear Information System (INIS)
de Saussure, G.; Perez, R.B.
1981-01-01
Several aspects of the measurement, analysis and evaluation of the cross sections of the fertile and fissile nuclides in the resonance regions are discussed. In the resolved range, for the fertile nuclides it is thought that the principal requirement for improved evaluations is for a practical methodology to deal with systematic errors and their correlations. For the fissile nuclides 235 U and 239 Pu, the ENDF/B-V evaluations are not consistent with ENDF/B procedures recommendations and fall short of the goals of resonance analysis. New evaluations of these two isotopes should be performed. In the unresolved resonance region it is shown that the ENDF/B representation is ambiguous and is not theoretically justified. A better representation may be desirable, and a validation of the representation with experimental self-shielding and transmission measurements is certainly required. 105 references
Duysebaev, A D; Kuchtina, I N; Sadykov, B M; Slusarenko, L I; Tokarevsky, V V; Fayans, S A
2001-01-01
A complex analysis of experimental data of elastic, inelastic scattering and total reactions cross-sections of alpha-particles on ^{90,94}Zr nuclei is performed. Values of the deformation lengths and neutron-proton multipole matrix elements relations for 2_{1}^{+}- and 3_{1}^{+}-states of ^{90,92,94,96}Zr nuclei for different types of particles are obtained. A comparative analysis is made. Experimental data for inelastic scattering of 35.4, 40.0, 50.1 and 65.0 MeV alpha-particles on ^{90,94}Zr nuclei are analysed for understanding the phase shifts in frames of the unified approach.
International Nuclear Information System (INIS)
Veyssiere, A.; Beil, H.; Bergere, R.; Carlos, P.; Fagot, J.; Lepretre, A.; Ahrens, J.
1979-01-01
A beam of 20-130 MeV positrons, with average intensities between 10 nA and 50 nA, is used at the 600 MeV Saclay Linac to create a quasi-monochromatic photon beam with a continuously variable energy. This beam was used to measure photoneutron cross sections and the corresponding photonuclear facility is first described. The computer-controlled methods, implemented to measure the energy spectrum and the emittance of the positron beam are described. The quasi-monochromatic photon lines are produced by the annihilation in flight of monoenergetic positrons in two annihilation radiators with different Z successively. The photon beam emission angle theta is shown to be the most critical parameter in the search for an optimum overall signal to background ratio for a specific photoneutron experiment. The choice of an angle theta approximately 4 0 is explained for absolute measurements of sigma(γ, xn) cross-sections, for which the used average intensities of monochromatic photons were thus purposely reduced to approximately 5 X 10 3 s -1 , with an energy resolution approximately 12%. (Auth.)
Cross-sections of residual nuclei from deuteron irradiation of thin thorium target at energy 7 GeV
Directory of Open Access Journals (Sweden)
Vespalec Radek
2017-01-01
Full Text Available The residual nuclei yields are of great importance for the estimation of basic radiation-technology characteristics (like a total target activity, production of long-lived nuclides etc. of accelerator driven systems planned for transmutation of spent nuclear fuel and for a design of radioisotopes production facilities. Experimental data are also essential for validation of nuclear codes describing various stages of a spallation reaction. Therefore, the main aim of this work is to add new experimental data in energy region of relativistic deuterons, as similar data are missing in nuclear databases. The sample made of thin natural thorium foil was irradiated at JINR Nuclotron accelerator with a deuteron beam of the total kinetic energy 7 GeV. Integral number of deuterons was determined with the use of aluminum activation detectors. Products of deuteron induced spallation reaction were qualified and quantified by means of gamma-ray spectroscopy method. Several important spectroscopic corrections were applied to obtain results of high accuracy. Experimental cumulative and independent cross-sections were determined for more than 80 isotopes including meta-stable isomers. The total uncertainty of results rarely exceeded 9%. Experimental results were compared with MCNP6.1 Monte-Carlo code predictions. Generally, experimental and calculated cross-sections are in a reasonably good agreement, with the exception of a few light isotopes in a fragmentation region, where the calculations are highly under-estimated. Measured data will be useful for future development of high-energy nuclear codes. After completion, final data will be added into the EXFOR database.
International Nuclear Information System (INIS)
Alfimenkov, V.P.; Mareev, Yu.D.; Novitskii, V.V.; Pikel'ner, L.B.; Skoi, V.R.
1994-01-01
Properties of lanthanum are investigated in an experiment on the interaction of polarized neutrons with polarized La nuclei. The total cross section for lanthanum is measured for neutron energies ranging from 0.4 to 10 eV. It is shown that one strong level below the neutron binding energy is sufficient for obtaining a good description of the lanthanum cross section in this energy range. The results on the cross section for the interaction of polarized projectiles on a polarized target confirm this conclusion. The spin of the 138 La neutron resonance at 3.0 eV is found to be J = 11 / 2 . 13 refs., 3 figs
Optimization aspects of the new nELBE photo-neutron source
Directory of Open Access Journals (Sweden)
Schwengner R.
2010-10-01
Full Text Available The nELBE beamline at Forschungszentrum Dresden-Rossendorf (FZD provides intense neutron beams by stopping primary electrons in a liquid lead target, where neutrons are produced by bremsstrahlung photons via (γ,n reactions. With the aim to increase the neutron yield through the enhancement of the electron beam energy (from the current 40 MeV limit up to 50 MeV, as well as to minimize several sources of background that are presently affecting the measurements, a new neutron beam-line and a new, larger neutron experimental room have been designed. The optimization of the neutron/photon ratio, the minimization of the backscattered radiation from the walls and the possibility to have better experimental conditions are the main advantages of the new design. To optimize the beamline, extensive simulations with the particle interaction and transport code FLUKA have been performed. Starting from the primary electron beam, both the photon and neutron radiation fields have been fully characterized. To have a cross-check of the results, the calculated values of the neutron yields at different energies of the primary beam have been compared both with an independent simulation with the MCNP code and with analytical calculations, obtaining a very satisfactory agreement at the level of few percent. The evaluated radiation fields have been used to optimize the direction of the new neutron beamline, in order to minimize the photon flash contribution. A general overview of the new photo-neutron source, together with all the steps of the optimization study, is here presented and discussed.
Energy Technology Data Exchange (ETDEWEB)
Atchison, F.
1998-09-01
The PSIMECX library contains calculated nuclide production cross-sections from neutron-induced reactions in the energy range about 2 to 800 MeV in the following 72 stable isotopes of 24 elements: {sup 12}C, {sup 13}C, {sup 16}O, {sup 17}O, {sup 18}O, {sup 23}Na, {sup 24}Mg, {sup 25}Mg, {sup 26}Mg, {sup 27}Al, {sup 28}Si, {sup 29}Si, {sup 30}Si, {sup 31}P, {sup 32}S, {sup 33}S, {sup 34}S, {sup 36}S, {sup 35}Cl, {sup 37}Cl, {sup 39}K, {sup 40}K, {sup 41}K, {sup 40}Ca, {sup 42}Ca, {sup 43}Ca, {sup 44}Ca, {sup 46}Ca, {sup 48}Ca, {sup 46}Ti, {sup 47}Ti, {sup 48}Ti, {sup 49}Ti, {sup 50}Ti, {sup 50}V, {sup 51}V, {sup 50}Cr, {sup 52}Cr, {sup 53}Cr, {sup 54}Cr, {sup 55}Mn, {sup 54}Fe, {sup 56}Fe, {sup 57}Fe, {sup 58}Fe, {sup 58}Ni, {sup 60}Ni, {sup 61}Ni, {sup 62}Ni, {sup 64}Ni, {sup 63}Cu, {sup 65}Cu, {sup 64}Zn, {sup 66}Zn, {sup 67}Zn, {sup 68}Zn, {sup 70}Zn, {sup 92}Mo, {sup 94}Mo, {sup 95}Mo, {sup 96}Mo, {sup 97}Mo, {sup 98}Mo, {sup 100}Mo, {sup 121}Sb, {sup 123}Sb, {sup 204}Pb, {sup 206}Pb, {sup 207}Pb, {sup 208}Pb, {sup 232}Th and {sup 238}U. The energy range covers essentially all transmutation channels other than capture. The majority of the selected elements are main constituents of normal materials of construction used in and around accelerator facilities and the library is, first and foremost, designed to be a tool for the estimation of their activation in wide-band neutron fields. This third report describes and discusses the calculational methods used for the heavy nuclei. The library itself has been described in the first report of this series and the treatment for the medium and light mass nuclei is given in the second. (author)
Photoneutrons from medical linear accelerators--radiobiological measurements and risk estimates
International Nuclear Information System (INIS)
Hall, Eric J.; Martin, Stewart G.; Amols, Howard; Hei, Tom K.
1995-01-01
Purpose: To assess the oncogenic potential of the photoneutrons produced by high energy medical linear accelerators. Methods and Materials: An established line of cells of rodent origin (C 3 H 10T1/2) was used to assess the oncogenic potential of the radiation dose received in the breast of an anthropomorphic 'randoman' phanton, while the cervix received a dose of 70 Gy. Experiments were performed at 6 MV, below the threshold for the production of photoneutrons, and at 20 MV where the dose includes about 0.01 Gy of photoneutrons as well as scattered x-rays. Results: A significantly higher transformation incidence was observed for the 20-MV machine, consistent with the measured neutron dose of about 0.01 Gy and a quality factor of 20. Conclusion: An estimate can be made of the additional deaths from second malignancies that might result from the photoneutrons generated by higher energy linear accelerators (Linacs), which must be offset against the possible improvements in survival that might result from the higher tumor doses made possible by the increased percentage depth doses
Spectra of photoneutrons produced by high energy X-ray radiotherapy linacs
Czech Academy of Sciences Publication Activity Database
Králík, M.; Turek, Karel
2008-01-01
Roč. 132, č. 1 (2008), s. 13-17 ISSN 0144-8420 Institutional research plan: CEZ:AV0Z10480505 Keywords : photoneutrons * Bonner spectrometer * track detectors Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 0.951, year: 2008
International Nuclear Information System (INIS)
Scharff-Goldhaber, G.
1979-01-01
It was shown previously that, below a critical angular momentum, yrast bands of nonmagic nuclei are well described by the two-parameter variable moment of inertia model. Some striking exceptions to this rule are found in nuclei which have the same mass number as doubly magic nuclei but possess either one (or two) proton pairs beyond a magic number and one (or two) neutron hole pairs, or vice versa. Yrast bands in these pseudomagic nuclei resemble those in magic nuclei. 17 references
International Nuclear Information System (INIS)
Tel, E.; Kisoglu, H. F.; Topaksu, A. K.; Aydin, A.; Kaplan, A.
2007-01-01
There are several new technological application fields of fast neutrons such as accelerator-driven incineration/ transmutation of the long-lived radioactive nuclear wastes (in particular transuranium nuclides) to short-lived or stable isotopes by secondary spallation neutrons produced by high-intensity, intermediate-energy, charged-particle beams, prolonged planetary space missions, shielding for particle accelerators. Especially, accelerator driven subcritical systems (ADS) can be used for fission energy production and /or nuclear waste transmutation as well as in the intermediate-energy accelerator driven neutron sources, ions and neutrons with energies beyond 20 MeV, the upper limit of exiting data files that produced for fusion and fission applications. In these systems, the neutron scattering cross sections and emission differential data are very important for reactor neutronics calculations. The transition rate calculation involves the introduction of the parameter of mean free path determines the mean free path of the nucleon in the nuclear matter. This parameter allows an increase in mean free path, with simulation of effect, which is not considered in the calculations, such as conservation of parity and angular momentum in intra nuclear transitions. In this study, we have investigated the multiple preequilibrium matrix element constant from internal transition for Uranium, Thorium, (n,xn) neutron emission spectra. The neutron-emission spectra produced by (n,xn) reactions on nuclei of some target (for spallation) have been calculated. In the calculations, we have used the geometry dependent hybrid model and the cascade exciton model including the effects of the preequilibrium. The pre-equilibrium direct effects have been examined by using full exciton model. All calculated results have been compared with the experimental data. The obtained results have been discussed and compared with the available experimental data and found agreement with each other
International Nuclear Information System (INIS)
Murahira, S.; Satoh, Y.; Honda, N.; Shibata, M.; Yamamoto, H.; Kawade, K.; Takahashi, A.; Iida, T.
1996-01-01
Thirteen neutron activation cross sections for (n,2n), (n,p), (n,np) and (n,α) reactions producing short-lived nuclei with half-lives between 56 s and 24 min were measured in the energy range from 13.4 MeV to 14.9 MeV for Pr, Ba, Ce, Sm, W, Sn and Hf. The cross sections of 179 Hf(n,np) 178m Lu and 180 Hf(n,p) 180 Lu were measured for the first time. (author)
International Nuclear Information System (INIS)
Khouaja, A.
2003-12-01
Using the direct method, the mean energy integrated reaction cross section was investigated for a wide range of neutron-rich nuclei (N → Ar) at GANIL. Using the parametrisation of S. Kox, 19 new radii measurements (reaction cross sections) were obtained. By the isotopic, isotonic and isospin dependence, the evolution of the strong reduced radius was studied according to the excess of neutrons. New halo effect is proposed to the nuclei of Mg 35 and S 44 . A quadratic parametrization is also proposed for the nuclear radius as a function of the isospin in the region of closed shells N=8 and N=28. In addition, we used a modified version of the Glauber model for studying the tail and matter distribution of nuclei. Indeed, using our new data the effects of the nuclear size (root mean square radii) and the matter distribution (diffusivity) were de-convoluted for each isotope. The root mean square radii of Na and Mg isotopes obtained so far were consistent with the ones from literature. (author)
Spectrin-like proteins in plant nuclei
Ruijter, de N.C.A.; Ketelaar, T.; Blumenthal, S.S.D.; Emons, A.M.C.; Schel, J.H.N.
2000-01-01
We analysed the presence and localization of spectrin-like proteins in nuclei of various plant tissues, using several anti-erythrocyte spectrin antibodies on isolated pea nuclei and nuclei in cells. Western blots of extracted purified pea nuclei show a cross-reactive pair of bands at 220–240 kDa,
International Nuclear Information System (INIS)
Aydin, A.; Yalim, H.A.; Tel, E.; Sarer, B.; Unal, R.; Sarpuen, I.H.; Kaplan, A.; Dag, M.
2009-01-01
This study aims to show the dependence on the choice of the ratio of the level density parameters a f and a n corresponding to the saddle point of fission and equilibrium deformation of nucleus, respectively, of the proton induced fission cross sections of some subactinide targets. The method was employed using different level density parameter ratios for each fission cross section calculation in ALICE/ASH computer code. The ALICE/ASH code calculations were compared both with the available experimental data and with the Prokofiev systematics data. It is found that the fission cross sections dependent heavily on the choice of level density parameter ratio in the fission and neutron emission channels, a f /a n , for some subactinide nuclei. To get a good description of the measured fission cross sections for subactinide nuclei, we used a ratio of the level density parameters in the fission and neutron emission channels, a f /a n , depending both on the target-nucleus and on the energy of the projectile, in agreement with results published in literature.
International Nuclear Information System (INIS)
Sari, A.; Carrel, F.; Gmar, M.; Laine, F.; Normand, S.; Lyoussi, A.
2012-01-01
The solution for management of a nuclear waste package is chosen according to its radiological characteristics. One of the most important of these features is the α-activity which is due to actinides ( 235 U, 238 U, 239 Pu, etc.) If non-destructive passive methods are not sufficient to quantify the latter, non-destructive active methods based on the fission process represent a solution of interest. First, these methods consist in irradiating a package in order to induce fission reactions on the actinides, and then, to detect the prompt and delayed particles which are emitted following these reactions. Our aim is to conduct neutron interrogation measurements on nuclear waste packages using an electron accelerator as a photoneutron generator. One of the main interests of this approach is that the intensity of the neutron flux can be one or two orders of magnitude higher than the one delivered by a deuterium-tritium generator. With the objective of improving nuclear waste characterization, the development of this method could enable the integration of three complementary techniques on a single measurement cell (active neutron interrogation, active photon interrogation, and high-energy imaging). In this paper, simulation and experimental results are presented. A simulation study using MCNPX has been conducted in order to determine the characteristics of the photoneutron flux emitted by the electron accelerator of the SAPHIR facility owned by CEA LIST. Energy spectra, angular distribution and intensity of the photoneutron flux have been obtained. A photoneutron interrogation measurement cell based on this accelerator has been built and assessed by carrying out measurements on uranium samples. Delayed gamma-ray spectra have been acquired and enabled to confirm the experimental feasibility of our method. (authors)
An accelerator-based epithermal photoneutron source for boron neutron capture therapy
Energy Technology Data Exchange (ETDEWEB)
Mitchell, Hannah E. [Georgia Inst. of Technology, Atlanta, GA (United States)
1996-04-01
Boron neutron capture therapy is an experimental binary cancer radiotherapy modality in which a boronated pharmaceutical that preferentially accumulates in malignant tissue is first administered, followed by exposing the tissue in the treatment volume to a thermal neutron field. Current usable beams are reactor-based but a viable alternative is the production of an epithermal neutron beam from an accelerator. Current literature cites various proposed accelerator-based designs, most of which are based on proton beams with beryllium or lithium targets. This dissertation examines the efficacy of a novel approach to BNCT treatments that incorporates an electron linear accelerator in the production of a photoneutron source. This source may help to resolve some of the present concerns associated with accelerator sources, including that of target cooling. The photoneutron production process is discussed as a possible alternate source of neutrons for eventual BNCT treatments for cancer. A conceptual design to produce epithermal photoneutrons by high photons (due to bremsstrahlung) impinging on deuterium targets is presented along with computational and experimental neutron production data. A clinically acceptable filtered epithermal neutron flux on the order of 10^{7} neutrons per second per milliampere of electron current is shown to be obtainable. Additionally, the neutron beam is modified and characterized for BNCT applications by employing two unique moderating materials (an Al/AlF_{3} composite and a stacked Al/Teflon design) at various incident electron energies.
An accelerator-based epithermal photoneutron source for boron neutron capture therapy
International Nuclear Information System (INIS)
Mitchell, H.E.
1996-04-01
Boron neutron capture therapy is an experimental binary cancer radiotherapy modality in which a boronated pharmaceutical that preferentially accumulates in malignant tissue is first administered, followed by exposing the tissue in the treatment volume to a thermal neutron field. Current usable beams are reactor-based but a viable alternative is the production of an epithermal neutron beam from an accelerator. Current literature cites various proposed accelerator-based designs, most of which are based on proton beams with beryllium or lithium targets. This dissertation examines the efficacy of a novel approach to BNCT treatments that incorporates an electron linear accelerator in the production of a photoneutron source. This source may help to resolve some of the present concerns associated with accelerator sources, including that of target cooling. The photoneutron production process is discussed as a possible alternate source of neutrons for eventual BNCT treatments for cancer. A conceptual design to produce epithermal photoneutrons by high photons (due to bremsstrahlung) impinging on deuterium targets is presented along with computational and experimental neutron production data. A clinically acceptable filtered epithermal neutron flux on the order of 10 7 neutrons per second per milliampere of electron current is shown to be obtainable. Additionally, the neutron beam is modified and characterized for BNCT applications by employing two unique moderating materials (an Al/AlF 3 composite and a stacked Al/Teflon design) at various incident electron energies
The photoneutron yield predictions by PICA and comparison with the measurements
International Nuclear Information System (INIS)
Job, P.K.; Gabriel, T.A.
1995-01-01
The photoneutron yields at higher photon energies have become very important since the advent of high energy electron accelerators. Bremsstrahlung is produced when the particle beam interacts with the storage-ring components or residual-gas molecules in the storage-ring vacuum. Bremsstrahlung thus produced interacts with the high-Z materials in the beamline like the beam dumps and collimators to produce photoneutrons. There are three modes of neutron production by bremsstrahlung. At low energies (≥525 MeV), photons are absorbed by the dipole interaction and the compound nucleus thus formed decays emitting protons and neutrons and other heavier particles. At higher energies (≥25 MeV), photon interacts with the nucleus through absorption on a quasi-deuteron, which subsequently decays producing a neutron and proton pair which can interact with the rest of the nucleus. At still higher energies the photopion production becomes possible and competes with the quasi-deuteron process. In this paper we have calculated the photoneutron yield from a thick copper target using the photonuclear interaction code PICA. Using this as the neutron source, we have calculated the dose rates through heavy concrete and compared it with the measurements made at the Advanced Photon Source at Argonne National Lab
Measurement of cross sections producing short-lived nuclei by 14MeV neutron. Cd, Sn, Te, Nd, Gd, Re
Energy Technology Data Exchange (ETDEWEB)
Sakane, H.; Yamamoto, H.; Kawade, K. [Nagoya Univ. (Japan); Iida, T.; Takahashi, A.
1998-03-01
Nine neutron activation cross sections producing the nuclei with half-lives between 25sec and 22min were measured at energy range between 13.4 and 14.9 MeV by activation method. The (n,p) and (n,{alpha}) reaction cross sections were measured for the isotopes of {sup 110}Cd, {sup 112}Sn, {sup 122}Te, {sup 130}Te and {sup 185}Re and those of {sup 130}Te, {sup 148}Nd and {sup 158}Gd, respectively. The present results were compared with our systematics proposed on the basis of 58 cross section data of (n,p) and 33 data of (n,{alpha}) reaction. Good agreements have been seen between them. (author)
Energy Technology Data Exchange (ETDEWEB)
Kabdrakhimova, G. D., E-mail: gaukharkd@gmail.com [L.N.Gumilyov Eurasian National University (Kazakhstan); Sobolev, Yu. G.; Kuhtina, I. N. [Joint Institute for Nuclear Research (Russian Federation); Kuterbekov, K. A. [L.N.Gumilyov Eurasian National University (Kazakhstan); Mendibaev, K. O.; Penionzhkevich, Yu. E. [Joint Institute for Nuclear Research (Russian Federation)
2017-01-15
Experimental excitation functions in terms of the total cross sections for {sup 6}He + Si nuclear reactions are analyzed in the energy range between 5 and 50 MeV/A, and a brief survey of the procedures used to obtain experimental data is given. Particular attention is given to describing experiments performed in beams of radioactive nuclei from the accelerators of the Laboratory of Nuclear Reactions at the Joint Institute for Nuclear Research (JINR, Dubna). The experimental data in question are analyzed on the basis of a semimicroscopic optical model.
International Nuclear Information System (INIS)
Villari, A.C.C.
1990-01-01
The actual tendencies to study exotic nuclei; applications of exotic nuclei beams in material study and medicine; recent results obtained by GANIL and Berkeley Laboratories of measurements of binding energy and radii of light nuclei; the future experiences to be carry out in several international laboratories and; proposal of studies in Brazil using Pelletron-USP accelerator and the LINAC superconductor accelerator, in construction in the same laboratory, are presented. (M.C.K.)
International Nuclear Information System (INIS)
Kobayashi, T.; Tanihata, I.; Suzuki, T.
1992-01-01
Transverse momentum distributions of the projectile fragments from β-unstable nuclei have been measured with various projectile and target combinations. The momentum correlation of two neutrons in the neutron halo is extracted from the P c t distribution of 9 Li and hat of the neutrons. It is found that the two neutrons are moving in the same direction on average and thus strongly suggests the formation of a di-neutron in 11 Li. (Author)
Yang, Yigang; Zhang, Zhi; Chen, Huaibi; Li, Yulan; Li, Yuanjing
2017-07-01
Contraband-detection systems can use X-rays and photoneutrons delivered from the same 7-MeV electron linear accelerator (e-LINAC) to stimulate and extract information from inspected materials. The X-ray attenuation information is used to measure the mass thickness, which is combined with the photoneutron attenuation information to categorize inspected materials as common organic materials, metals, and heavy metals. Once a heavy metal is found, the beta-delayed neutrons stimulated by the (γ,fission) reaction are measured by a polyethylene-moderated 3He counter to clarify if the material is fissile. The presence of neutron events 2000 μs after the X-ray pulse confirms the existence of the fissile material. The isotopes in the material are then identified using the time-of-flight method to analyze the resonant attenuation of the fissile material to the 10-1-102 eV photoneutrons emitted from and thermalized by the D2O photonto-neutron convertor, which converts X-rays to photoneutrons. Eight high-Z simulants are tested to confirm the feasibility of identifying the isotopes from the photoneutron resonance. The underlying principles and experimental results are discussed.
Occupational doses due to photoneutrons in medical linear accelerators rooms
International Nuclear Information System (INIS)
Soares, Alessandro Facure Neves de Salles
2006-04-01
Medical linear accelerators, with maximum photon energies above 10 MeV, are becoming of common use in Brazil. Although desirable in the therapeutic point of view, the increase in photon energies causes the generation of undesired neutrons, which are produced through nuclear reactions between photons and the high Z target nuclei of the materials that constitute the accelerator head. In this work, MCNP simulation was undertaken to examine the neutron equivalent doses around the accelerators head and at the entrance of medical linear accelerators treatment rooms, some of them licensed in Brazil by the National Regulatory Agency (CNEN). The simulated neutron dose equivalents varied between 2 e 26 μ Sv/Gy RX , and the results were compared with calculations performed with the use of some semi-empirical equations found in literature. It was found that the semi-empirical equations underestimate the simulated neutron doses in the majority of the cases, if compared to the simulated values, suggesting that these equations must be revised, due to the increasing number of high energy machines in the country. (author)
Photoneutron source based on a compact 10 MeV betatron
International Nuclear Information System (INIS)
Chakhlov, V.L.; Bell, Z.W.; Golovkov, V.M.; Shtein, M.M.
1999-01-01
Accelerator-based photoneutron sources have enjoyed wide use and offer the advantages of long term stability, ease of control and absence of radioactive materials. We report here measurements of the yield of photoneutrons from a neutron generator using a compact betatron. Electrons were accelerated to energies up to 10 MeV and produced a bremsstrahlung beam with a dose rate of 0.16 Gy/min (at 10 MeV, 1 m from the bremsstrahlung target) to irradiate LiD, Be, depleted U, and Pb neutron-producing targets. The angular distributions of photoneutrons produced by bremsstrahlung beams were measured with a 'long' counter and integrated to determine neutron yield. In addition, neutron time of flight spectra were recorded from all targets using a 15.5 m flight path perpendicular to the photon beam. The maximum observed yields were 4.6x10 7 n/s obtained with 1 kg of LiD, 5.7x10 7 n/s from a 3.3 kg Be block, 6.2x10 6 n/s from 1.5 kg of depleted U, and 7.0x10 6 n/s from 10.7 kg of Pb. Optimization of target dimensions, shape, and positioning is expected to increase the yield from the LiD target by a factor of 35, while optimization of the other targets is expected to yield at most a factor of 10. With the increased yield and a deuteride target, this compact betatron-based system could find application in the interrogation of waste containers for fissile material
Photoneutron source based on a compact 10 MeV betatron
International Nuclear Information System (INIS)
Bell, Z.W.; Chaklov, V.L.; Golovkov, V.M.
1998-01-01
Accelerator-based photoneutron sources have enjoyed wide use and offer the advantages of long term stability, ease of control and absence of radioactive materials. The authors report here measurements of the yield of photoneutrons from a neutron generator using a compact betatron (466 kg total weight, 900 by 560 by 350 mm betatron dimensions) at the Institute of Introscopy of the Tomsk Polytechnic University. Electrons were accelerated to energies up to 10 MeV and produced a bremsstrahlung beam with a dose rate of 0.16 Gy/min (at 10 MeV, 1 meter from the bremsstrahlung target) to irradiate LiD, Be, depleted U, and Pb neutron-producing targets. The angular distributions of photoneutrons produced by bremsstrahlung beams were measured with a long counter and integrated to determine neutron yield. In addition, neutron time of flight spectra were recorded from all targets using a 15 meter flight path perpendicular to the photon beam. The maximum observed yields were 5.2 x 10 4 n/rad/gram target obtained with LiD, 1.7 x 10 4 n/rad/gram from Be, 3.3 x 10 3 n/rad/gram from U, and 7.5 x 10 2 n/rad/gram from Pb. Optimization of target dimensions, shape, and positioning is expected to increase the yield from the LiD target by a factor of 35. With the increased yield, this compact betatron-based system could find application in the interrogation of waste containers for fissile material
International Nuclear Information System (INIS)
Mittig, W.; Plagnol, E.; Schutz, Y.
1989-11-01
A new simple direct method for the measurement of the total reaction cross section (σ R ) for several light radioactive nuclei (A≤40) is developed. From that, the reduced strong absorption radii (r o 2 ) are obtained. A comparison is made with data obtained by other techniques. A strong isospin dependence of the nuclear radii is observed. (L.C.) [pt
Total cross section measurements with π- , Σ- and protons on nuclei and nucleons around 600 GeV/c
International Nuclear Information System (INIS)
Dersch, U.; Akchurin, N.; Andreev, V.A.; Atamantchouk, A.G.; Aykac, M.; Balatz, M.Y.; Bondar, N.F.; Bravar, A.; Cooper, P.S.; Dauwe, L.J.; Davidenko, G.V.; Dirkes, G.; Dolgolenko, A.G.; Dreossi, D.; Dzyubenko, G.B.; Edelstein, R.; Emediato, L.; Endler, A.M.F.; Engelfried, J.; Eschrich, I.; Escobar, C.O.; Evdokimov, A.V.; Filimonov, I.S.; Garcia, F.G.; Gaspero, M.; Gerzon, S.; Giller, I.; Golovtsov, V.L.; Goncharenko, Y.M.; Gottschalk, E.; Gouffon, P.; Grachov, O.A.; Guelmez, E.; Kangling, He; Iori, M.; Jun, S.Y.; Kamenskii, A.D.; Kaya, M.; Kilmer, J.; Kim, V.T.; Kochenda, L.M.; Koenigsmann, K.; Konorov, I.; Kozhevnikov, A.P.; Krivshich, A.G.; Krueger, H.; Kubantsev, M.A.; Kubarovsky, V.P.; Kulyavtsev, A.I.; Kuropatkin, N.P.; Kurshetsov, V.F.; Kushnirenko, A.; Kwan, S.; Lach, J.; Lamberto, A.; Landsberg, L.G.; Larin, I.; Leikin, E.M.; Yunshan, Li; Zhigang, Li; Luksys, M.; Lungov, T.; Magarrel, D.; Maleev, V.P.; Mao, D.; Chensheng, Mao; Zhenlin, Mao; Masciocchi, S.; Mathew, P.; Mattson, M.; Matveev, V.; McCliment, E.; McKenna, S.L.; Moinester, M.A.; Molchanov, V.V.; Morelos, A.; Mukhin, V.A.; Nelson, K.D.; Nemitkin, A.V.; Neoustroev, P.V.; Newsom, C.; Nilov, A.P.; Nurushev, S.B.; Ocherashvili, A.; Oleynik, G.; Onel, Y.; Ozel, E.; Ozkorucuklu, S.; Patrichev, S.; Penzo, A.; Petrenko, S.I.; Pogodin, P.; Povh, B.; Procario, M.; Prutskoi, V.A.; Ramberg, E.; Rapazzo, G.F.; Razmyslovich, B.V.; Rud, V.I.; Russ, J.; Scheglov, Y.; Schiavon, P.; Semyatchkin, V.K.; Simon, J.; Sitnikov, A.I.; Skow, D.; Smith, V.J.; Srivastava, M.; Steiner, V.; Stepanov, V.; Stutte, L.; Svoiski, M.; Terentyev, N.K.; Thomas, G.P.; Uvarov, L.N.; Vasiliev, A.N.; Vavilov, D.V.; Verebryusov, V.S.; Victorov, V.A.; Vishnyakov, V.E.; Vorobyov, A.A.; Vorwalter, K.; You, J.; Wenheng, Zhao; Shuchen, Zheng; Zukanovich-Funchal, R.
2000-01-01
Total cross sections for Σ - and π - on beryllium, carbon, polyethylene and copper as well as total cross sections for protons on beryllium and carbon have been measured in a broad momentum range around 600 GeV/c . These measurements were performed with a transmission technique in the SELEX hyperon-beam experiment at Fermilab. We report on results obtained for hadron-nucleus cross sections and on results for σ tot (Σ - N) and σ tot (π - N) , which were deduced from nuclear cross sections
International Nuclear Information System (INIS)
Van'kov, A.A.
1994-01-01
The contradiction between a measured integral neutron absorption cross-section averaged over a fast reactor spectrum and the corresponding value which was calculated with the use of evaluated microscopic cross-sections and a theoretical neutron spectrum has been investigated. The possible systematic error of a correction factor which takes into account multiple resonance neutron scattering in samples used in the measurement of the absorption cross-section is investigated. It is proposed that this error may be one of the main reason for the contradiction mentioned above which arises in the measurement of the 236 U neutron absorption cross-section. (author). 13 refs, 3 figs
Energy Technology Data Exchange (ETDEWEB)
Miklukho, O. V., E-mail: miklukho-ov@pnpi.rncki.ru; Kisselev, A. Yu., E-mail: kisselev@mail.desy.de; Amalsky, G. M.; Andreev, V. A.; Gavrilov, G. E.; Izotov, A. A.; Kozlenko, N. G.; Kravchenko, P. V.; Levchenko, M. P.; Novinskiy, D. V.; Prokofiev, A. N., E-mail: prokofiev-an@pnpi.rncki.ru; Shvedchikov, A. V.; Trush, S. I.; Zhdanov, A. A. [National Research Centre Kurchatov Institute, Petersburg Nuclear Physics Institute (Russian Federation)
2017-03-15
The polarization of secondary protons in the (p, p’) inelastic reactions on {sup 40}Ca and {sup 12}C nuclei at the initial proton energy of 1 GeV was measured over a wide range of scattered-proton momenta at a laboratory angle of Θ = 21°. The reaction cross sections were also measured. Scattered protons were detected by means of magnetic spectrometer equipped with a polarimeter based on multiwire-proportional chambers. A structure in the polarization and cross-section data, which is probably related to scattering off nucleon correlations in the nuclei involved, was observed.
International Nuclear Information System (INIS)
Shimoura, S.
1992-01-01
The relation between nuclear density distribution and interaction cross section is discussed in terms of Glauber model. Based on the model, density distribution of neutron drip-line nucleus 11 Be and 11 Li is determined experimentally from incident energy dependence of interaction cross sections of 11 Be and 11 Li on light targets. The obtained distributions have long tails corresponding to neutron halos of loosely bound neutrons. (Author)
Angular distributions of threshold photoneutrons from 208Pb
International Nuclear Information System (INIS)
Haacke, L.C.
1973-01-01
The shape of the 41 keV resonance in the 208 Pb(γ,n) 207 Pb reaction has been considered in some detail in view of recent reports of asymmetry interpreted in terms of interference between resonant and nonresonant neutron capture amplitudes. Additional threshold measurements were made using bremsstrahlung with an endpoint energy of 8.0 MeV. It has been concluded that asymmetry in the present data appears to be induced by the presence of an unresolved resonance, and that this interpretation of the resonance shape cannot be confuted on the basis of (n,γ) or total neutron cross section measurements made elsewhere. (author)
Energy Technology Data Exchange (ETDEWEB)
Mirazita, M. [INFN, Laboratori Nazionali di Frascati, Rome (Italy)
1998-03-01
The total photoabsorption cross section on several nuclei has been measured in the energy range 0.5 - 2.6 GeV. Nuclear data show a significant reduction of the absorption strength with respect to the free nucleon case suggesting a shadowing effect at low energies.
Photo-neutron yields from thin and thick targets irradiated by 2.0 GeV electrons
International Nuclear Information System (INIS)
Hee-Seock, Lee; Syuichi, Ban; Toshiya, Sanami; Kazutoshi, Takahashi; Tatsuhiko, Sato; Kazuo, Shin
2005-01-01
The photo-neutron yields from thin and thick targets irradiated by high energy electrons were studied. The photo-neutron spectra at 90 deg C relative to the incident 2.0 GeV electrons were measured by the pulsed beam time-of-flight technique using the Pilot-U plastic scintillator and the NE213 liquid scintillator with 2 inches in length and 2 inches in diameter. Targets, from low-Z element (carbon) to high-Z element (bismuth) and with thin (0.5 Xo) and thick (10 Xo) thickness, were used in this study. The differential photo-neutron yields between 2 MeV (mainly 8 MeV) and 400 MeV were obtained. The systematics was studied to make empirical yield terms for shielding application. Recently, the study of the angular distributed yields was conducted at two other observing angles, 48 deg C and 140 deg C. The photo-neutron yields between 8 MeV and 250 MeV were obtained for thick targets. The experimental data were compared with results calculated using the EGS4+PICA3 or the MCNPX 2.5d code. (authors)
Energy Technology Data Exchange (ETDEWEB)
Kim, Yeon Su; Yoon, In Ha; Bae, Sun Myeong; Kang, Tae Young; Baek, Geum Mun; Kim, Sung Hwan; Nam, Uk Won; Lee, Jae Jin; Park, Yeong Sik [Dept. of Radiation Oncology, ASAN Medical Center, Seoul (Korea, Republic of)
2014-12-15
Photoneutron dose in high-energy photon radiotherapy at linear accelerator increase the risk for secondary cancer. The purpose of this investigation is to evaluate the dose variation of photoneutron with different treatment method, flattening filter, dose rate and gantry angle in radiation therapy with high-energy photon beam (E≥8 MeV). TrueBeam STxTM(Ver1.5, Varian, USA) and Korea Tissue Equivalent Proportional Counter (KTEPC) were used to detect the photoneutron dose out of the high-energy photon field. Complex Patient plans using Eclipse planning system (Version 10.0, Varian, USA) was used to experiment with different treatment technique(IMRT, VMAT), condition of flattening filter and three different dose rate. Scattered photoneutron dose was measured at eight different gantry angles with open field (Field size : 5×5cm). The mean values of the detected photoneutron dose from IMRT and VMAT were 449.7 μSv, 2940.7 μSv. The mean values of the detected photoneutron dose with Flattening Filter(FF) and Flattening Filter Free(FFF) were measured as 2940.7 μSv, 232.0 μSv. The mean values of the photoneutron dose for each test plan (case 1, case 2 and case 3) with FFF at the three different dose rate (400, 1200, 2400 MU/min) were 3242.5 μSv, 3189.4 μSv, 3191.2 μSv with case 1, 3493.2 μSv, 3482.6 μSv, 3477.2 μSv with case 2 and 4592.2 μSv, 4580.0 μSv, 4542.3 μSv with case 3, respectively. The mean values of the photoneutron dose at eight different gantry angles ( 0° , 45°, 90°, 135°, 180°, 225°, 270° , 315°) were measured as 3.2 μSv, 4.3 μSv, 5.3 μSv, 11.3 μSv, 14.7 μSv, 11.2 μSv, 3.7 μSv, 3.0 μSv at 10 MV and as 373.7 μSv, 369.6 μSv, 384.4 μSv, 423.6 μSv, 447.1 μSv, 448.0 μSv, 384.5 μSv, 377.3 μSv at 15MV. As a result, it is possible to reduce photoneutron dose using FFF mode and VMAT method with TrueBeam STxTM. The risk for secondary cancer of the patients will be decreased with continuous evaluation of the photoneutron dose.
International Nuclear Information System (INIS)
Janssens, R.V.F.; Khoo, T.L.
1991-01-01
Superdeformation was first proposed some twenty years ago to explain the fission isomers observed in some actinide nuclei. It was later realized that superdeformed shapes can occur at high angular momentum in lighter nuclei. The interest in the mechanisms responsible for these exotic shapes has increased enormously with the discovery of a superdeformed band of nineteen discrete lines in 152 Dy (8). At about the same time, evidence for highly deformed nuclei (axis ratio 3:2) was also reported near 132 Ce(9). Striking properties emerged from the first experiments, such as the essentially constant energy spacing between transitions (picket-fence spectra), the unexpectedly strong population of superdeformed bands at high spins, and the apparent lack of a link between the superdeformed states and the yrast levels. These findings were reviewed by Nolan and Twin. The present article follows upon their work and discusses the wealth of information that has since become available. This includes the discovery of a new island of superdeformation near A = 190, the detailed spectroscopy of ground and excited bands in the superdeformed well near A = 150 and A = 190, the surprising occurrence of superdeformed bands with identical transition energies in nuclei differing by one or two mass units, and the improved understanding of mechanisms responsible for the feeding into and the decay out of the superdeformed states
Measurement of formation cross sections of short-lived nuclei by 14 MeV neutron. Nd, Sm, Dy, Er, Yb
Energy Technology Data Exchange (ETDEWEB)
Sakane, H.; Yamamoto, H.; Kawade, K. [Nagoya Univ. (Japan). School of Engineering; Iida, T.; Takahashi, A.
1997-03-01
Eight neutron activation cross sections producing the nuclei with half-lives between 3 min and 24 min were obtained at the energy range between 13.4 and 14.9 MeV by activation method. The cross sections were {sup 146}Nd(n,p){sup 146}Pr, {sup 154}Sm(n,{alpha}){sup 151}Nd, {sup 162}Dy(n,p){sup 162}Tb, {sup 163}Dy(n,np){sup 162}Tb, {sup 163}Dy(n,p){sup 163}Tb, {sup 164}Dy(n,p){sup 164}Tb, {sup 170}Er(n,{alpha}){sup 167}Dy, {sup 174}Yb(n,p){sup 170}Tm. {sup 163}Dy(n,np){sup 162}Tb (T{sub 1/2}=7.7 min) was obtained for the first time. Present results are compared with previous results and the evaluated data of JENDL-3 and ENDF/B-VI. There are some discrepancies between present results and the JENDL-3 and ENDF/B-VI. (author)
Energy Technology Data Exchange (ETDEWEB)
Kotov, A.A.; Gavrikov, Yu.A.; Vaishnene, L.A.; Vovchenko, V.G.; Poliakov, V.V.; Fedorov, O.Ya.; Chestnov, Yu.A.; Shchetkovskiy, A.I [Petersburg Nuclear Physics Institute, Gatchina, Leningrad district, Orlova roscha 1, 188300 (Russian Federation); Fukahori, T. [Japan Atomic Energy Research Institute, Tokai-mura, Ibaraki 319-1195 (Japan)
2005-07-01
The results of the total fission cross sections measurements for {sup nat}Pb, {sup 209}Bi, {sup 232}Th, {sup 233}U, {sup 235}U, {sup 238}U, {sup 237}Np and {sup 239}Pu nuclei at the energy proton range 200-1000 MeV are presented. Experiments were carried out at 1 GeV synchrocyclotron of Petersburg Nuclear Physics Institute (Gatchina). The measurement method is based on the registration in coincidence of both complementary fission fragments by two gas parallel plate avalanche counters, located at a short distance and opposite sides of investigated target. The insensitivity of parallel plate avalanche counters to neutron and light charged particles allowed us to place the counters together with target immediately in the proton beam providing a large solid angle acceptance for fission fragment registration and reliable identification of fission events. The proton flux on the target to be studied was determined by direct counting of protons by scintillation telescope. The measured energy dependence of the total fission cross sections is presented. Obtained results are compared with other experimental data as well as with calculation in the frame of the cascade evaporation model. (authors)
Photoneutron strengths in 26Mg at energies of astrophysical interest
deBoer, R. J.; Best, A.; Görres, J.; Smith, K.; Tan, W.; Wiescher, M.; Raut, R.; Rusev, G.; Tonchev, A. P.; Tornow, W.
2014-05-01
Background: The 22Ne(α,n)25Mg reaction is an important source of neutrons for s-process nucleosynthesis. The neutron production from the reaction is quite sensitive to the low-energy cross section, which is dominated by narrow resonances. The high level density of the 26Mg compound nucleus above the α separation energy prevents simple extrapolations from higher energy and the high Coulomb barrier makes the direct measurements extremely difficult. For this reason, indirect methods must be employed to study the level properties of 26Mg. Purpose: The current measurement utilizes the reaction 26Mg(γ,n)25Mg to probe the level structure of the 26Mg compound nucleus from the neutron-separation energy at 11.093 MeV up to Ex≈ 12 MeV. Methods: The High-Intensity γ-ray Source of the Triangle Universities Nuclear Laboratory was used to bombard a ˜16 g sample of enriched 26Mg oxide and the resulting decay neutrons were detected with an array of nine liquid scintillator detectors. Neutron time-of-flight peaks with corresponding energies as low as ˜50 keV were detected. An efficiency measurement of the detectors was made at the University of Notre Dame's nuclear science laboratory to energies as low as 45 keV. Results: Five resonances were observed at Eγ = 11.150, 11.289, 11.329, 11.506, and 11.749 MeV and their strengths have been extracted. Conclusion:. The resulting strengths at Eγ = 11.289, 11.329, 11.506, and 11.749 MeV are in good agreement with previous measurements. The strength of the resonance at Eγ = 11.150 MeV is somewhat lower than previously measured but is in reasonable agreement when systematic uncertainties are considered. The results are also consistent with those of 25Mg(n,γ)26Mg studies where a comparison shows that many of the resonances observed here are the result of multiple unresolved narrow resonances.
International Nuclear Information System (INIS)
Chasnikov, I.Ya.; Izbasarov, M.I.; Vinitsky, A.Kh.; Abdinov, O.B.; Agakishiev, G.N.; Backovic, S.; Damianovich, V.; Drndarevic, S.; Krmpotic, D.; Krpic, D.
1981-12-01
Experimental data on inelastic cross sections and PI - -meson production in interactions initiated by protons with the incident momentum in the range (2-10) GeV/c and by deuterons, alphas and carbon nuclei with the incident momentum per nucleon in the range (2-5) GeV/c on carbon and tantalum target-nuclei are presented. The experimental data have been obtained using the 2 m propane bubble chamber. The analysis of the experimental data has been made in the framework of various theoretical models. (authors)
International Nuclear Information System (INIS)
Balian, Roger; Remaud, Bernard; Suraud, E.; Durand, Dominique; Tamain, Bernard; Gobbi, A.; Cugnon, J.; Drapier, Olivier; Govaerts, Jan; Prieels, Rene
1995-09-01
This 14. international school Joliot-Curie of nuclear physic deals with nuclei in collision at high energy. Nine lectures are included in the proceedings of this summer school: 1 - From statistical mechanics outside equilibrium to transport equations (Balian, R.); 2 - Modeling of heavy ions reactions (Remaud, B.); 3 - Kinetic equations in heavy ions physics (Suraud, E.); 4 - Colliding nuclei near the Fermi energy (Durand, D.; Tamain, B.); 5 - From the Fermi to the relativistic energy domain: which observable? For which physics? (Gobbi, A.); 6 - Collisions at relativistic and ultra relativistic energies, Theoretical aspects (Cugnon, J.); 7 - Quark-gluon plasma: experimental signatures (Drapier, O.); 8 - Electroweak interaction: a window on physics beyond the standard model (Govaerts, J.); 9 - Symmetry tests in β nuclear process: polarization techniques (Prieels, R.)
Energy Technology Data Exchange (ETDEWEB)
Back, B.B.; Blumenthal, D.J.; Davids, C.N. [and others
1995-08-01
In this experiment we tried to measure the evaporation residue cross section over a wide range of beam energies for the {sup 100}Mo + {sup 116}Cd reaction using the FMA. However, because of longer-than-estimated runs needed at each beam energy, and the difficulty of bending evaporation residues at the higher energies in the FMA, data were taken only at beam energies of E{sub beam} = 460, 490, and 521 MeV, which correspond to excitation energies of E{sub exc} = 62, 78, and 95 MeV, respectively. By comparing to results for the {sup 32}S + {sup 184}W reactions measured recently, we expect to demonstrate a strong entrance channel effect related to the hindrance of complete fusion in near-symmetric heavy systems (a fusion hindrance factor of the order 7-10 is expected on the basis of the Extra-Push Model). The data are being analyzed.
Energy Technology Data Exchange (ETDEWEB)
Yang, Oh Nam [Dept. of Radiology, Mokpo Science University, Mokpo (Korea, Republic of); Lim, Cheong Hwan [Dept. of Radiological Science, Hanseo University, Seosan (Korea, Republic of)
2017-06-15
In this study, the generation of photoneutrons between the 10 MV FF mode and the FFF mode was evaluated and the amount of photoneutrons generated by the 10 MV and 15 MV energy changes in the FFF mode was evaluated. The generated neutrons were evaluated at 13 measurement points and the KTEPC was used to collect the generated neutrons. 10 MV FF mode was measured at 10 MV FF mode and FFF mode at all measurement points. In the superior direction, 0.455mSv and 0.152mSv were the largest, and more than 33% optical neutron was generated in FF. 10 MV in FFF mode, 15 MV in 15 MV, and 0.402 mSv in the direction of Superior, and 6.9% in the direction.
International Nuclear Information System (INIS)
Whipple, R.E.; Grant, P.M.; Daniels, R.J.; Daniels, W.R.; O'Brien, H.A.Jr.
1976-01-01
As the precursor of its 88 Y daughter, 88 Zr could be advantageously included in the active component of the 88 Y-Be photoneutron source for several reasons. The spallation of Mo targets with medium-energy protons at LAMPF procedure has been developed to separate radiozirconium from the target material and various spallogenic impurities. 88 Zr can consequently be obtained carrier-free and in quantitative yield. (author)
Abou-Taleb, W M; Hassan, M H; El Mallah, E A; Kotb, S M
2018-05-01
Photoneutron production, and the dose equivalent, in the head assembly of the 15 MV Elekta Precise medical linac; operating in the faculty of Medicine at Alexandria University were estimated with the MCNP5 code. Photoneutron spectra were calculated in air and inside a water phantom to different depths as a function of the radiation field sizes. The maximum neutron fluence is 3.346×10 -9 n/cm 2 -e for a 30×30 cm 2 field size to 2-4 cm-depth in the phantom. The dose equivalent due to fast neutron increases as the field size increases, being a maximum of 0.912 ± 0.05 mSv/Gy at depth between 2 and 4 cm in the water phantom for 40×40 cm 2 field size. Photoneutron fluence and dose equivalent are larger to 100 cm from the isocenter than to 35 cm from the treatment room wall. Copyright © 2018 Elsevier Ltd. All rights reserved.
International Nuclear Information System (INIS)
Anon.
1995-01-01
The recent detection of intergalactic helium by NASA's Astro-2 mission backs up two earlier measurements by ESA and the University of California, San Diego, using instruments aboard the Hubble Space Telescope. Taken together, these results give strong evidence that this helium is primordial, confirming a key prediction of the Big Bang theory. The amount of helium the results imply could also account for some of the Universe's invisible dark matter - material which affects galactic motion but is otherwise undetectable. According to theory, helium nuclei formed at around 100 seconds after the Big Bang, but the amount of helium depended on even earlier events. Initially, protons turned into neutrons with the same probability that neutrons turned into protons. But after about one second, the Universe had cooled down enough for the weak interaction to freeze out. Neutrons continued to decay into the slightly lighter protons, whilst the opposite reaction became much more scarce. At around 100 seconds, thermonuclear fusion reactions could begin, and all the neutrons that were left became absorbed into helium nuclei, leaving the remaining protons locked up in hydrogen. The ratio of helium to hydrogen was therefore determined by events occurring when the Universe was just one second old. Standard models of primordial nucleosynthesis fix this ratio at slightly less than 2 5% by mass. All heavier elements were cooked up much later in the stars, and amount to less than 1 % of the Universe's mass. These predictions have been borne out remarkably well by observation, although proof of the primordial origins of hydrogen and helium has remained elusive until now. Big Bang nucleosynthesis goes on to estimate that primordial baryonic matter in the form of light nuclei could account for around 10% of the Universe's dark matter. All three recent measurements used the same technique of looking at distant quasars, some of the most luminous objects in the Universe, to
On the distribution of quarks in nuclei
International Nuclear Information System (INIS)
Baldin, A.M.; Panebrattsev, V.S.; Stavinskij, V.S.
1984-01-01
On the basis of the data on cumulative proton, deuteron and nuclear fragment production in hadr on-nucleon reactions and deep inelastic muon-nucleon scattering quark distributions in light, intemediate and heavy nuclei have been investigated. Conditions of limiting fragmentation of hadrons and nuclei in the studied processes have been investigated to obtain quark-parton structure functions (Gs 2 ) of the studied hadrons or nuclei. Invariant differential cross sections of π + , π - , K + meson production on aluminium, deuterium and lead nuclei and their dependence on scale variable at the transverse momentum value Psub(T) approximately 0 have been obtained. Properties of structure functions G 2 and behaviour of different nuclei differential cross sections of limiting fragmentation have been investigated. It is concluded that considered regularities testify to the presence of multiquark states in nuclei, different by its structure from nUcleons
International Nuclear Information System (INIS)
Atchison, F.
1998-09-01
The PSIMECX library contains calculated nuclide production cross-sections from neutron-induced reactions in the energy range about 2 to 800 MeV in the following 72 stable isotopes of 24 elements: 12 C, 13 C, 16 O, 17 O, 18 O, 23 Na, 24 Mg, 25 Mg, 26 Mg, 27 Al, 28 Si, 29 Si, 30 Si, 31 P, 32 S, 33 S, 34 S, 36 S, 35 Cl, 37 Cl, 39 K, 40 K, 41 K, 40 Ca, 42 Ca, 43 Ca, 44 Ca, 46 Ca, 48 Ca, 46 Ti, 47 Ti, 48 Ti, 49 Ti, 50 Ti, 50 V, 51 V, 50 Cr, 52 Cr, 53 Cr, 54 Cr, 55 Mn, 54 Fe, 56 Fe, 57 Fe, 58 Fe, 58 Ni, 60 Ni, 61 Ni, 62 Ni, 64 Ni, 63 Cu, 65 Cu, 64 Zn, 66 Zn, 67 Zn, 68 Zn, 70 Zn, 92 Mo, 94 Mo, 95 Mo, 96 Mo, 97 Mo, 98 Mo, 100 Mo, 121 Sb, 123 Sb, 204 Pb, 206 Pb, 207 Pb, 208 Pb, 232 Th and 238 U. The energy range covers essentially all transmutation channels other than capture. The majority of the selected elements are principal constituents of normal materials of construction used in and around accelerator facilities and the library is, first and foremost, designed to be a tool for the estimation of their activation in wide-band neutron fields. This second report, of a series of three, describes and discusses the calculational methods used for the stable isotopes up to and including 123 Sb. The library itself has been described in the first report of the series and the treatment for the heavy nuclei is given in the third. (author)
Diffraction scattering and disintegration of 3He nuclei by atomic nuclei
International Nuclear Information System (INIS)
Koval'chuk, V.I.
2006-01-01
Within diffraction model framework a method of cross sections calculation for scattering and disintegration of weakly-bounded two-clustered nuclei by nuclei when both of its clusters are changed has been proposed. The experimental elastic scattering cross sections of 3 He by 40 Ca, 90 Zr and coincidence spectra of disintegration products from 28 Si( 3 He,dp) have been described
{sup 124}Sb–Be photo-neutron source for BNCT: Is it possible?
Energy Technology Data Exchange (ETDEWEB)
Golshanian, Mohadeseh [Nuclear Science and Technology Research Institute (NSTRI), Tehran (Iran, Islamic Republic of); Department of Physics, Shahrood University, Shahrood (Iran, Islamic Republic of); Rajabi, Ali Akbar [Department of Physics, Shahrood University, Shahrood (Iran, Islamic Republic of); Kasesaz, Yaser, E-mail: ykasesaz@aeoi.org.ir [Nuclear Science and Technology Research Institute (NSTRI), Tehran (Iran, Islamic Republic of)
2016-11-01
In this research a computational feasibility study has been done on the use of {sup 124}SbBe photo-neutron source for Boron Neutron Capture Therapy (BNCT) using MCNPX Monte Carlo code. For this purpose, a special beam shaping assembly has been designed to provide an appropriate epithermal neutron beam suitable for BNCT. The final result shows that using 150 kCi of {sup 124}Sb, the epithermal neutron flux at the designed beam exit is 0.23×10{sup 9} (n/cm{sup 2} s). In-phantom dose analysis indicates that treatment time for a brain tumor is about 40 min which is a reasonable time. This high activity {sup 124}Sb could be achieved using three 50 kCi rods of {sup 124}Sb which can be produced in a research reactor. It is clear, that as this activity is several hundred times the activity of a typical cobalt radiotherapy source, issues related to handling, safety and security must be addressed.
Energy Technology Data Exchange (ETDEWEB)
Atchison, F.
1998-09-01
The PSIMECX library contains calculated nuclide production cross-sections from neutron-induced reactions in the energy range about 2 to 800 MeV in the following 72 stable isotopes of 24 elements: {sup 12}C, {sup 13}C, {sup 16}O, {sup 17}O, {sup 18}O, {sup 23}Na, {sup 24}Mg, {sup 25}Mg, {sup 26}Mg, {sup 27}Al, {sup 28}Si, {sup 29}Si, {sup 30}Si, {sup 31}P, {sup 32}S, {sup 33}S, {sup 34}S, {sup 36}S, {sup 35}Cl, {sup 37}Cl, {sup 39}K, {sup 40}K, {sup 41}K, {sup 40}Ca, {sup 42}Ca, {sup 43}Ca, {sup 44}Ca, {sup 46}Ca, {sup 48}Ca, {sup 46}Ti, {sup 47}Ti, {sup 48}Ti, {sup 49}Ti, {sup 50}Ti, {sup 50}V, {sup 51}V, {sup 50}Cr, {sup 52}Cr, {sup 53}Cr, {sup 54}Cr, {sup 55}Mn, {sup 54}Fe, {sup 56}Fe, {sup 57}Fe, {sup 58}Fe, {sup 58}Ni, {sup 60}Ni, {sup 61}Ni, {sup 62}Ni, {sup 64}Ni, {sup 63}Cu, {sup 65}Cu, {sup 64}Zn, {sup 66}Zn, {sup 67}Zn, {sup 68}Zn, {sup 70}Zn, {sup 92}Mo, {sup 94}Mo, {sup 95}Mo, {sup 96}Mo, {sup 97}Mo, {sup 98}Mo, {sup 100}Mo, {sup 121}Sb, {sup 123}Sb, {sup 204}Pb, {sup 206}Pb, {sup 207}Pb, {sup 208}Pb, {sup 232}Th and {sup 238}U. The energy range covers essentially all transmutation channels other than capture. The majority of the selected elements are principal constituents of normal materials of construction used in and around accelerator facilities and the library is, first and foremost, designed to be a tool for the estimation of their activation in wide-band neutron fields. This second report, of a series of three, describes and discusses the calculational methods used for the stable isotopes up to and including {sup 123}Sb. The library itself has been described in the first report of the series and the treatment for the heavy nuclei is given in the third. (author)
Energy Technology Data Exchange (ETDEWEB)
Yang, Oh Nam [Gangneung Asan Hospital, Gangneung (Korea, Republic of); Yang, Oh Nam; Lim, Cheong Hwan [Hanseo Univ., Seosan (Korea, Republic of)
2012-12-15
Intensity-modulated radiotherapy(IMRT) have the ability to provide better dose conformity and sparing of critical normal tissues than three-dimensional radiotherapy(3DCRT). Especially, with the benefit of health insurance in 2011, its use now increasingly in many modern radiotherapy departments. Also the use of linear accelerator with high-energy photon beams over 10 MV is increasing. As is well known, these linacs have the capacity to produce photoneutrons due to photonuclear reactions in materials with a large atomic number such as the target, flattening filters, collimators, and multi-leaf collimators(MLC). MLC-based IMRT treatments increase the monitor units and the probability of production of photoneutrons from photon-induced nuclear reactions. The purpose of this study is to quantitatively evaluate the dose of photoneutrons produced from 3DCRT and IMRT technique for Rando phantom in cervical cancer. We performed the treatment plans with 3DCRT and IMRT technique using Rando phantom for treatment of cervical cancer. An Rando phantom placed on the couch in the supine position was irradiated using 15 MV photon beams. Optically stimulated luminescence dosimeters(OSLD) were attached to 4 different locations (abdomen, chest, head and neck, eyes) and from center of field size and measured 5 times each of locations. Measured neutron dose from IMRT technique increased by 9.0, 8.6, 8.8, and 14 times than 3DCRT technique for abdomen, chest, head and neck, and eyes, respectively. When using IMRT with 15 MV photon beams, the photoneutrons contributed a significant portion on out-of-field. It is difficult to prevent high energy photon beams to produce the photoneutrons due to physical properties, if necessary, It is difficult to prevent high energy photon beams to produce the photoneutrons due to physical properties, if necessary, it is need to provide the additional safe shielding on a linear accelerator and should therefore reduce the out-of-field dose.
International Nuclear Information System (INIS)
Yang, Oh Nam; Yang, Oh Nam; Lim, Cheong Hwan
2012-01-01
Intensity-modulated radiotherapy(IMRT) have the ability to provide better dose conformity and sparing of critical normal tissues than three-dimensional radiotherapy(3DCRT). Especially, with the benefit of health insurance in 2011, its use now increasingly in many modern radiotherapy departments. Also the use of linear accelerator with high-energy photon beams over 10 MV is increasing. As is well known, these linacs have the capacity to produce photoneutrons due to photonuclear reactions in materials with a large atomic number such as the target, flattening filters, collimators, and multi-leaf collimators(MLC). MLC-based IMRT treatments increase the monitor units and the probability of production of photoneutrons from photon-induced nuclear reactions. The purpose of this study is to quantitatively evaluate the dose of photoneutrons produced from 3DCRT and IMRT technique for Rando phantom in cervical cancer. We performed the treatment plans with 3DCRT and IMRT technique using Rando phantom for treatment of cervical cancer. An Rando phantom placed on the couch in the supine position was irradiated using 15 MV photon beams. Optically stimulated luminescence dosimeters(OSLD) were attached to 4 different locations (abdomen, chest, head and neck, eyes) and from center of field size and measured 5 times each of locations. Measured neutron dose from IMRT technique increased by 9.0, 8.6, 8.8, and 14 times than 3DCRT technique for abdomen, chest, head and neck, and eyes, respectively. When using IMRT with 15 MV photon beams, the photoneutrons contributed a significant portion on out-of-field. It is difficult to prevent high energy photon beams to produce the photoneutrons due to physical properties, if necessary, It is difficult to prevent high energy photon beams to produce the photoneutrons due to physical properties, if necessary, it is need to provide the additional safe shielding on a linear accelerator and should therefore reduce the out-of-field dose
Neutron scattering on deformed nuclei
International Nuclear Information System (INIS)
Hansen, L.F.; Haight, R.C.; Pohl, B.A.; Wong, C.; Lagrange, C.
1984-09-01
Measurements of neutron elastic and inelastic differential cross sections around 14 MeV for 9 Be, C, 181 Ta, 232 Th, 238 U and 239 Pu have been analyzed using a coupled channel (CC) formalism for deformed nuclei and phenomenological global optical model potentials (OMP). For the actinide targets these results are compared with the predictions of a semi-microscopic calculation using Jeukenne, Lejeune and Mahaux (JLM) microscopic OMP and a deformed ground state nuclear density. The overall agreement between calculations and the measurements is reasonable good even for the very light nuclei, where the quality of the fits is better than those obtained with spherical OMP
Czech Academy of Sciences Publication Activity Database
Khouaja, A.; Villari, A.; Baiborodin, Dmitri; Dlouhý, Zdeněk; Savajols, H.
2005-01-01
Roč. 25, - (2005), s. 223-226 ISSN 1434-6001 R&D Projects: GA ČR GA202/04/0791 Institutional research plan: CEZ:AV0Z1048901 Keywords : neutron-rich nuclei * deformation * isotopes Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 1.659, year: 2005
International Nuclear Information System (INIS)
Blokhin, A.I.; Degtyarev, I.I.
2002-01-01
In this paper the results of physical verification for the BOFOD photonuclear data files are reported, available for the uranium isotopes U 235 , U 238 . These results were compared with calculated data by the parameterization driven model of photonuclear reaction and experimental data. Experimental data of photoneutron yields from surface of uranium sphere irradiated by 28 MeV electrons are used for a verification. Both calculations have been carried out with the RTS and T general purpose Monte Carlo code with detailed electron-photon-nucleon transport simulation using the ENDF/B-VI and EPDL evaluated data libraries
Spectra and absorbed dose by photo-neutrons in a solid water mannequin exposed to a Linac of 15 MV
International Nuclear Information System (INIS)
Benites R, J.; Vega C, H. R.; Velazquez F, J.
2012-10-01
Using Monte Carlo methods was modeled a solid water mannequin; according to the ICRU 44 (1989), Tissue substitutes in radiation dosimetry and measurements, of the International Commission on Radiation Units and Measurements; Report 44. This material Wt 1 is made of H (8.1%), C (67.2%), N (2.4%), O (19.9%), Cl (0.1%), Ca (2.3%) and its density is of 1.02 gr/cm 3 . The mannequin was put instead of the patient, inside the treatment room and the spectra and absorbed dose were determined by photo-neutrons exposed to a Linac of 15 MV. (Author)
Incidence of centrally positioned nuclei in mouse masticatory muscle fibers
DEFF Research Database (Denmark)
Vilmann, A; Vilmann, H; Kirkeby, S
1989-01-01
Cross-sections of normal digastric, temporalis and masseter muscles from 7- and 30-week-old mice were studied for centrally positioned nuclei. Such nuclei were inhomogeneously distributed throughout each muscle and varied markedly between specimens. The incidence of centrally positioned nuclei in...
Energy Technology Data Exchange (ETDEWEB)
Tsechanski, A. [Ben-Gurion University of the Negev, Department of Nuclear Engineering, P.O. Box 653, Beer-Sheva 84105 (Israel); Bielajew, A.F. [Department of Nuclear Engineering and Radiological Sciences, The University of Michigan, 2355 Bonisteel Boulevard, Ann Arbor, MI 48109 (United States); Archambault, J.P.; Mainegra-Hing, E. [National Research Council of Canada, Ionizing Radiation Standards Laboratory, Ottawa, ON K1A 0R6 (Canada)
2016-01-01
A new “one-stage” approach for production of {sup 99}Mo and other radioisotopes by means of an electron linear accelerator is described. It is based on using a molybdenum target both as a bremsstrahlung converter and as a radioisotope producing target for the production of {sup 99}Mo via the photoneutron reaction {sup 100}Mo(γ,n){sup 99}Mo. Bremsstrahlung characteristics, such as bremsstrahlung efficiency, angular distribution, and energy deposition for molybdenum targets were obtained by means of the EGSnrc Monte Carlo simulation code system. As a result of our simulations, it is concluded that a 60 MeV electron beam incident on a thick Mo target will have greater bremsstrahlung efficiency than the same thickness (in units of r{sub 0}) W target, for target thickness z > 1.84r{sub 0}, where r{sub 0} is the electron range. A 50 MeV electron beam incident on a Mo target will result in greater bremsstrahlung efficiency than the same thickness W target (in units of r{sub 0}) for target thickness case: z ⩾ 2.0r{sub 0}. It is shown for the one-stage approach with thicknesses of (1.84–2.0)r{sub 0}, that the {sup 99}Mo-production bremsstrahlung efficiency of a molybdenum target is greater by ∼100% at 30 MeV and by ∼70% at 60 MeV compared to the values for tungsten of the same thickness (in units of the appropriate r{sub 0}) in the traditional two-stage approach (W converter and separate {sup 99}Mo producing target). This advantage of the one-stage approach arises from the fact that the bremsstrahlung produced is attenuated only once from attenuation in the molybdenum converter/target. In the traditional, two-stage approach, the bremsstrahlung generated in the W-converter/target is attenuated both in the converter in the {sup 99}Mo-producing molybdenum target. The photoneutron production yield of molybdenum and tantalum (as a substitute for tungsten) target was calculated by means of the MCNP5 transport code. On the basis of these data, the specific activity
Cross section of ternary fission of Al, Ti, Co and Zr nuclei induced by 0,8 - 1,8 Gev photons
International Nuclear Information System (INIS)
Lima, D.A. de; Sousa, E.V. de; Milomen, W.C.C.; Tavares, O.A.P.
1988-01-01
A research on ternary fission of Al, Ti, Co, and Zr nuclei induced by bremsstrahlung photons of 0,8, 1,0, 1,4, and 1,8 Gev end-point energies has been carried out using makrofol polycarbonate and CR-39 polymer as fission-track detectors. Results are discussed and compared with other ternary fission data. (M.W.O.) [pt
Çeçen, Yiğit; Gülümser, Tuğçe; Yazgan, Çağrı; Dapo, Haris; Üstün, Mahmut; Boztosun, Ismail
2017-09-01
In cancer treatment, high energy X-rays are used which are produced by linear accelerators (LINACs). If the energy of these beams is over 8 MeV, photonuclear reactions occur between the bremsstrahlung photons and the metallic parts of the LINAC. As a result of these interactions, neutrons are also produced as secondary radiation products (γ,n) which are called photoneutrons. The study aims to map the photoneutron flux distribution within the LINAC bunker via neutron activation analysis (NAA) using indium-cadmium foils. Irradiations made at different gantry angles (0°, 90°, 180° and 270°) with a total of 91 positions in the Philips SLI-25 linear accelerator treatment room and location-based distribution of thermal neutron flux was obtained. Gamma spectrum analysis was carried out with high purity germanium (HPGe) detector. Results of the analysis showed that the maximum neutron flux in the room occurred at just above of the LINAC head (1.2x105 neutrons/cm2.s) which is compatible with an americium-beryllium (Am-Be) neutron source. There was a 90% decrease of flux at the walls and at the start of the maze with respect to the maximum neutron flux. And, just in front of the LINAC door, inside the room, neutron flux was measured less than 1% of the maximum.
International Nuclear Information System (INIS)
Lee, H. S.; Park, J. S.; Choi, H. D.; Sato, Tatsuhiko; Shin, Kasuo; Ban, Syuichi
2000-01-01
Above the Giant Dipole Resonance (GDR) region, high energy photoneutron spectra produced by irradiation of 2.04 GeV electrons into Pb target were measured by Time-of-Flight (TOF) technique. The differential photoneutron yields were obtained at a fixed angle of 90 degrees to the electron beam direction. The TOF system consists of Pilot-U plastic scintillation detector, which has fast response time, and the high speed multiscaler or CAMAC TDC. In the improvement of experimental setup to extend the flight distance to 10.4 m lead to make the measurable energy to 500 MeV from 300 MeV. And using the TDC based electronics lead to use a veto counter. The results were compared with the calculated one by using EGS4 and Modified PICA95. The characteristics of this TOF system was introduced in this paper and the results for several measuring conditions, which are flight distance, TOF electronics, and type of neutron detector, were discussed to improve the accuracy of this measurement
Carinou, Eleutheria; Stamatelatos, Ion Evangelos; Kamenopoulou, Vassiliki; Georgolopoulou, Paraskevi; Sandilos, Panayotis
The development of a computational model for the treatment head of a medical electron accelerator (Elekta/Philips SL-18) by the Monte Carlo code mcnp-4C2 is discussed. The model includes the major components of the accelerator head and a pmma phantom representing the patient body. Calculations were performed for a 14 MeV electron beam impinging on the accelerator target and a 10 cmx10 cm beam area at the isocentre. The model was used in order to predict the neutron ambient dose equivalent at the isocentre level and moreover the neutron absorbed dose distribution within the phantom. Calculations were validated against experimental measurements performed by gold foil activation detectors. The results of this study indicated that the equivalent dose at tissues or organs adjacent to the treatment field due to photoneutrons could be up to 10% of the total peripheral dose, for the specific accelerator characteristics examined. Therefore, photoneutrons should be taken into account when accurate dose calculations are required to sensitive tissues that are adjacent to the therapeutic X-ray beam. The method described can be extended to other accelerators and collimation configurations as well, upon specification of treatment head component dimensions, composition and nominal accelerating potential.
Directory of Open Access Journals (Sweden)
Çeçen Yiğit
2017-01-01
Full Text Available In cancer treatment, high energy X-rays are used which are produced by linear accelerators (LINACs. If the energy of these beams is over 8 MeV, photonuclear reactions occur between the bremsstrahlung photons and the metallic parts of the LINAC. As a result of these interactions, neutrons are also produced as secondary radiation products (γ,n which are called photoneutrons. The study aims to map the photoneutron flux distribution within the LINAC bunker via neutron activation analysis (NAA using indium-cadmium foils. Irradiations made at different gantry angles (0°, 90°, 180° and 270° with a total of 91 positions in the Philips SLI-25 linear accelerator treatment room and location-based distribution of thermal neutron flux was obtained. Gamma spectrum analysis was carried out with high purity germanium (HPGe detector. Results of the analysis showed that the maximum neutron flux in the room occurred at just above of the LINAC head (1.2x105 neutrons/cm2.s which is compatible with an americium-beryllium (Am-Be neutron source. There was a 90% decrease of flux at the walls and at the start of the maze with respect to the maximum neutron flux. And, just in front of the LINAC door, inside the room, neutron flux was measured less than 1% of the maximum.
International Nuclear Information System (INIS)
2000-01-01
The present collection of letters from JINR, Dubna, contains seven separate records on the integral representation for structure functions and target mass effects, multiscale properties of DNA primary structure including cross-scale correlations, dissipative evolution of the elementary act, the fine structure of the M T =1 Gamow-Teller resonance in 147g Tb→ 147 Gd β + /EC decay, the behaviour of the TVO temperature sensors in the magnetic fields, a fast method for searching for tracks in multilayer drift chambers of HADES spectrometer, a novel approach to particle track etching including surfactant enhanced control of pore morphology, azimuthal correlations of secondary particles in 32 S induced interactions with Ag(Br) nuclei at 4.5 GeV/ c/ nucleon
Fragmentation of relativistic nuclei
International Nuclear Information System (INIS)
Cork, B.
1975-06-01
Nuclei with energies of several GeV/n interact with hadrons and produce fragments that encompass the fields of nuclear physics, meson physics, and particle physics. Experimental results are now available to explore problems in nuclear physics such as the validity of the shell model to explain the momentum distribution of fragments, the contribution of giant dipole resonances to fragment production cross sections, the effective Coulomb barrier, and nuclear temperatures. A new approach to meson physics is possible by exploring the nucleon charge-exchange process. Particle physics problems are explored by measuring the energy and target dependence of isotope production cross sections, thus determining if limiting fragmentation and target factorization are valid, and measuring total cross sections to determine if the factorization relation, sigma/sub AB/ 2 = sigma/sub AA/ . sigma/sub BB/, is violated. Also, new experiments have been done to measure the angular distribution of fragments that could be explained as nuclear shock waves, and to explore for ultradense matter produced by very heavy ions incident on heavy atoms. (12 figures, 2 tables)
Combined Photoneutron And X Ray Interrogation Of Containers For Nuclear Materials
Gozani, Tsahi; Shaw, Timothy; King, Michael J.; Stevenson, John; Elsalim, Mashal; Brown, Craig; Condron, Cathie
2011-06-01
Effective cargo inspection systems for nuclear material detection require good penetration by the interrogating radiation, generation of a sufficient number of fissions, and strong and penetrating detection signatures. Inspection systems need also to be sensitive over a wide range of cargo types and densities encountered in daily commerce. Thus they need to be effective with highly hydrogenous cargo, where neutron attenuation is a major limitation, as well as with dense metallic cargo, where x-ray penetration is low. A system that interrogates cargo with both neutrons and x-rays can, in principle, achieve high performance over the widest range of cargos. Moreover, utilizing strong prompt-neutron (˜3 per fission) and delayed-gamma ray (˜7 per fission) signatures further strengthens the detection sensitivity across all cargo types. The complementary nature of x-rays and neutrons, used as both probing radiation and detection signatures, alleviates the need to employ exceedingly strong sources, which would otherwise be required to achieve adequate performance across all cargo types, if only one type of radiation probe were employed. A system based on the above principles, employing a commercially-available 9 MV linac was developed and designed. Neutrons are produced simultaneously with x-rays by the photonuclear interaction of the x-ray beam with a suitable converter. A total neutron yield on the order of 1011 n/s is achieved with an average electron beam current of 100 μA. If fissionable material is present, fissions are produced both by the high-energy x-ray beam and by the photoneutrons. Photofission and neutron fission dominate in hydrogenous and metallic cargos, respectively. Neutron-capture gamma rays provide information on the cargo composition. The prompt neutrons resulting from fission are detected by two independent detector systems: by very efficient Differential Die Away Analysis (DDAA) detectors, and by direct detection of neutrons with energies higher
International Nuclear Information System (INIS)
Sugimoto, Kenzo
1982-01-01
An experiment is proposed to determine systematically the radii of the nuclei produced through the projectile fragmentation process in high energy heavy-ion collision. The measurement of total reaction cross section using the projectile fragments of a single nuclide on a target give information about nuclear radii. The production cross section of the fragments is appreciable for many nuclides. Therefore, it is possible to map systematically the reaction radii of the nuclei which can be produced as the projectile fragments. In an experiment using the projectile fragments as the incident beam, the cross section can be expressed as a function of the radii of a projectile and a target. An experiment with He-8 produced by the fragmentation of C-12 is proposed. The He-8 has four neutrons in the p-3/2 orbit outside the He-4 core. Proton and neutron distributions for He isotopes were calculated on the basis of the Hartree-Fock method. The information related to this kind of distribution can be obtained by the proposed experiment. The nuclear structure effect is seen in the nuclear radii of other unstable nuclei. The experimental examples of the isotope shift measurement and the excitation energy are presented. (Kato, T.)
International Nuclear Information System (INIS)
Varlamov, V.V.; Ishkhanov, B.S.
2002-08-01
The majority of published data for photoneutron reaction both total and partial cross section data obtained using both bremsstrahlung and quasimonoenergetic photon beams has been analyzed systematically. The last kind data were treated separately for results obtained at USA National Lawrence Livermore Laboratory and at Centre d.Etudes Nucleaires de Saclay (France). It was found out that as a rule total photoneutron reaction cross sections obtained at Livermore differ (being smaller in amplitude) from that of other laboratories. The Saclay-Livermore data discrepancies were analyzed in details. Combined the result of this analysis with that of analysis of partial photoneutron reactions [(γ,n) + (γ,np)] and (γ,2n) cross sections balance between Livermore and Saclay data published before the following recommendation was formulated: for reliable balance of total photoneutron (γ,xn) and partial [(γ,n) + [(γ,np)] and (γ,2n) reactions cross section absolute values the Livermore (not Saclay) data must be used but multiplied to the parameter 1.122. Saclay total reaction data could be used directly but partial reaction data must be recalculated via complex procedure. (author)
Determining properties of baryon resonances in nuclei
International Nuclear Information System (INIS)
Johnson, M.B.; Chen, C.M.; Ernst, D.J.; Jiang, M.F.
1996-01-01
Meson-nucleus and photon-nucleus interactions are important sources of information about the medium modifications of baryon resonances in nuclei. Indications of how large the medium effects are for resonances above the Δ 33 (1232) are provided by it combined analysis of photonuclear and pion cross sections in the GeV range of energies. Tile existing data indicate a possible 10-20% renormalization of the pion coupling to higher-lying resonances in nuclei
Energy Technology Data Exchange (ETDEWEB)
Aleksanyan, A.S.; Babayan, G.E.; Voskanyan, A.V.; Gasparyan, A.D.; Gevorkyan, S.R.; Karapetyan, S.N.; Ketikyan, A.Z.; Megrabyan, G.K.; Movsisyan, K.A.; Oganesyan, G.A.; and others
1987-04-01
The differential cross sections for Compton scattering by nuclei of /sup 4//sub 2/ He have been measured at the momentum transfers 0.02less than or equal tochemically bondtchemically bond<0.14 (GeV/c)/sup 2/ in the energy region E/sub ..gamma../ = 1.8--3.8 GeV. On the basis of the diffraction theory of multiple scattering the values of the differential cross sections at t = 0, of the slope parameters of the diffraction cone, and of the /sup 4//sub 2/ He nucleus radius have been determined. Experimental values are given for the phase of the scattering amplitude by nucleons, ..cap alpha..( f/sup 0//sub i/) = Re f/sup 0//sub i// Im f/sup 0//sub i/. On the basis of the differential cross sections at t = 0 the total photoabsorption cross section and the photon screening coefficient are determined for the /sup 4//sub 2/ He nucleus.
International Nuclear Information System (INIS)
Angelique, J.C.; Orr, N.A.
1997-01-01
The study of the nuclei far off stability valley is of much interest for testing the nuclear models established for the stable nuclei but also for astrophysics to understand the nucleosynthesis. Experiments aim to measure the mass and lifetime, to build the decay schemes and also to study the structure and the properties of these nuclei. The radioactive beam group focused its research on light neutron-rich nuclei having a halo neutron structure. Mass measurements in N ∼ Z nuclei namely in A ∼ 60-80 proton-rich nuclei, important for understanding the rp process, are mentioned, as well as in nuclei in the 100 Sn region. In the newly obtained 26 O and 28 O nuclei the lifetimes, the probabilities of emission of one for more neutrons were determined. The data analysis has permitted to determine also for the first time the lifetimes of 27,29 F and 30 Ne. Studies of nuclei in the 100 Sn region, near the proton drip line in the ground and isomeric states are now under way. The spectroscopy (energy levels, gamma emissions, etc.) of the neutron-rich nuclei produced by the 36 S fragmentation has been carried out in 31 Ne, 17 B and 29 F. Studies by Coulomb excitation of the 2 + excited states and associated probability B (E2) in O, Ne, Ni and Zn are now analysed
International Nuclear Information System (INIS)
Chomaz, Ph.
2000-01-01
This document gathers the slides and their commentaries that have been presented at the conference 'physics and fundamental questions' by P. Chomaz. The author reviews the different quantum aspects of nuclei: tunnel effect, symmetries, magic numbers, wave functions, size, shapes and deformations. The author shows that nuclei are quantum objects of great complexity, their structures are not yet well understood and the study of exotic nuclei will continue bringing valuable information
Pairing correlations in nuclei
International Nuclear Information System (INIS)
Baba, C.V.K.
1988-01-01
There are many similarities between the properties of nucleons in nuclei and electrons in metals. In addition to the properties explainable in terms of independent particle motion, there are many important co-operative effects suggesting correlated motion. Pairing correlation which leads to superconductivity in metals and several important properties in nuclei , is an exmple of such correlations. An attempt has been made to review the effects of pairing correlations in nuclei. Recent indications of reduction in pairing correlations at high angular momenta is discussed. A comparision between pairing correlations in the cases of nuclei and electrons in metals is attempted. (author). 20 refs., 10 figs
Energy Technology Data Exchange (ETDEWEB)
Benites R, J. L.; Carrillo C, A. [Centro Estatal de Cancerologia de Nayarit, Av. Enfermeria, Fracc. Fray Junipero Serra, 63000 Tepic, Nayarit (Mexico); Vega C, H. R. [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Calle Cipres No. 10, Fracc. La Penuela, 98068 Zacatecas (Mexico); Velazquez F, J. B., E-mail: jlbenitesr@prodigy.net.mx [Universidad Autonoma de Nayarit, Posgrado CBAP, Carretera Tepic Compostela Km. 9, Xalisco, Nayarit (Mexico)
2011-10-15
Using the Monte Carlo code MCNP-5, the photons and photoneutrons spectra generated in the head stock of the lineal accelerator (Linac) Varian of 15 MV of the Cancerology State of Nayarit were determined. For the calculations a heterogeneous head stock was modeled, more compatible with the work conditions. In the center of the head stock a tungsten target was located on a copper support, followed by the flattened filter. The photons and photoneutrons spectra were obtained accelerating electrons and making them collide against the target to produce photons by Bremsstrahlung, these photons were transported inside the head stock and the photons and photoneutrons spectra were calculated in a punctual detector located under the flattened filter and in the isocenter. The spectra were evaluated in punctual detectors that were located in the plane from the isocenter to the long of the X and Y axes each 20 cm, in an equidistant way, up to 2 m, so much in the longitudinal and transversal axes. In the calculations were used histories 5E(6) with the purpose of obtaining smaller uncertainties to 1%. It was found that the photons spectrum in the punctual detector inside the head stock presents a pick of 1.25 MeV in the energy interval of 0.5 and 1.5 MeV, later suffers a filtration and diminishes in asymptote form. This spectrum modifies when the beam reaches the isocenter, diminishing the low energy photons. Inside the head stock the photoneutrons spectrum shows a structure with two picks, one before 1 MeV and other after 1 MeV; this is for effect of the collimators geometry and the distance. Finally an increment of the total neutrons flow to 60 cm of distance of the isocenter on the Y axis was observed, due to the design geometry of the modeling heterogeneous head stock. (Author)
International Nuclear Information System (INIS)
Bueyuekuslu, H.; Kaplan, A.; Aydin, A.; Tel, E.; Yildirim, G.
2010-01-01
In this study, proton total reaction cross sections have been investigated for some isotopes such as 12 C, 27 Al, 9 Be, 16 O, 181 Ta, 197 Au, 6 Li, and 14 N by a proton beam up to 600 MeV. Calculation of the proton total cross sections has been carried out by the analytic expression formulated by M.A. Alvi by using Coulomb-modified Glauber theory with the Helm model nuclear form factor. The obtained results have been discussed and compared with the available experimental data and found to be in agreement with each other.
International Nuclear Information System (INIS)
Lee, H. S.; Ban, S.; Sanami, T.; Takahashi, K.; Sato, T.; Shin, K.; Chung, C.
2005-01-01
A study of differential photo-neutron yields by irradiation with 2 GeV electrons has been carried out. In this extension of a previous study in which measurements were made at an angle of 90 deg. relative to incident electrons, the differential photo-neutron yield was obtained at two other angles, 48 deg. and 140 deg., to study its angular characteristics. Photo-neutron spectra were measured using a pulsed beam time-of-flight method and a BC418 plastic scintillator. The reliable range of neutron energy measurement was 8-250 MeV. The neutron spectra were measured for 10 Xo-thick Cu, Sn, W and Pb targets. The angular distribution characteristics, together with the previous results for 90 deg., are presented in the study. The experimental results are compared with Monte Carlo calculation results. The yields predicted by MCNPX 2.5 tend to underestimate the measured ones. The same trend holds for the comparison results using the EGS4 and PICA3 codes. (authors)
Lee, Hee-Seock; Ban, Syuichi; Sanami, Toshiya; Takahashi, Kazutoshi; Sato, Tatsuhiko; Shin, Kazuo; Chung, Chinwha
2005-01-01
A study of differential photo-neutron yields by irradiation with 2 GeV electrons has been carried out. In this extension of a previous study in which measurements were made at an angle of 90 degrees relative to incident electrons, the differential photo-neutron yield was obtained at two other angles, 48 degrees and 140 degrees, to study its angular characteristics. Photo-neutron spectra were measured using a pulsed beam time-of-flight method and a BC418 plastic scintillator. The reliable range of neutron energy measurement was 8-250 MeV. The neutron spectra were measured for 10 Xo-thick Cu, Sn, W and Pb targets. The angular distribution characteristics, together with the previous results for 90 degrees, are presented in the study. The experimental results are compared with Monte Carlo calculation results. The yields predicted by MCNPX 2.5 tend to underestimate the measured ones. The same trend holds for the comparison results using the EGS4 and PICA3 codes.
Nuclei with exotic constituents
International Nuclear Information System (INIS)
Yamazaki, Toshimitsu.
1990-08-01
We discuss various interesting features in the behavior of exotic constituents of nuclei such as hyperons and mesons, in particular, with emphases on the aspect of exotic halos which are formed in general by short-range repulsion and long-range attraction. Specifically, Λ and Σ hypernuclei and pionic nuclei are discussed. (author)
International Nuclear Information System (INIS)
Foucher, R.
1979-01-01
If some β - emitters are particularly interesting to study in light, medium, and heavy nuclei, another (and also) difficult problem is to know systematically the properties of these neutron rich nuclei far from the stability line. A review of some of their characteristics is presented. How far is it possible to be objective in the interpretation of data is questioned and implications are discussed
International Nuclear Information System (INIS)
Arenhoevel, H.
1977-01-01
The field of baryon resonances in nuclei is reviewed. Theoretical developments and experimental evidence as well are discussed. Special emphasis is laid on electromagnetic processes for the two nucleon system. Some aspects of real isobars in nuclei are touched upon. (orig.) [de
International Nuclear Information System (INIS)
Szymanski, Z.; Berger, J.F.; Heenen, P.H.; Heyde, K.; Haas, B.; Janssens, R.; Paya, D.; Gogny, D.; Huber, G.; Bjoernholm, S.; Brack, M.
1991-01-01
The purpose of 1991 Joliot-Curie Summer School is to review the most advances in the understanding of the nuclei physics after the considerable progress in gamma spectroscopy. It covers the following topics: Highly and super-deformed nuclei, nuclear structures, mean-field approach and beyond, fission isomers, nuclear excitations with long lifetime and metal clusters
International Nuclear Information System (INIS)
Shimizu, Yoshifumi
2009-01-01
Except for the closed shell nuclei, almost all nuclei are in the superconducting state at their ground states. This well-known pair correlation in nuclei causes various interesting phenomena. It is especially to be noted that the pair correlation becomes weak in the excited states of nuclei with high angular momentum, which leads to the pair phase transition to the normal state in the high spin limit. On the other hand, the pair correlation becomes stronger in the nuclei with lower nucleon density than in those with normal density. In the region of neutron halo or skin state of unstable nuclei, this phenomenon is expected to be further enhanced to be observed compared to the ground state of stable nuclei. An overview of those interesting aspects caused via the pair correlation is presented here in the sections titled 'pair correlations in ground states', pair correlations in high spin states' and 'pair correlations in unstable nuclei' focusing on the high spin state. (S. Funahashi)
International Nuclear Information System (INIS)
Liu, L.C.
1987-01-01
The possibility of producing eta-mesic nuclei by the use of pions is discussed. If these nuclei are observed experimentally, then the binding energies of the eta in this new nuclear matter can be used to extract accurately the eta-N-N* coupling constant in a nucleus. The framework for these calculations is the coupled channel isobar model
International Nuclear Information System (INIS)
Hlavac, S.; Benovic, M.; Betak, E.; Dostal, L.; Turzo, I.; Simakov, S.P.
1999-01-01
We measured cross section of prompt discrete γ ray transitions produced in 14.6 MeV neutron interactions with 23 Na, 27 Al, 28 Si, 31 P 39 K, 51 V, 55 Mn and nat Mo. Cross sections were measured relative to reference cross sections with low uncertainties using a dedicated experimental setup with a 244 cm 3 HPGe photon detector and associated α particle timing. In addition to photons from inelastic scattering we observed discrete transitions from (n,p), (n,n'p), (n,α), and (n,2n) reactions. Discrete γ transitions in 28 Si(n,n'p) 27 Al, the majority of transitions in Mn+n, and all transitions in Mo+n reactions were observed for the first time. Where available, our experimental data are compared with existing data. This comparison shows that existing data are in disagreement with present data in many cases, a finding which stresses the necessity of standardization of measurement procedure. For some reactions we compared our results with statistical model predictions, calculated with the advanced code GNASH as well as with a technically simpler code DEGAS, developed in our lab. In several instances, mostly in reactions where only a single nucleon is emitted, the statistical model calculations describe the observed cross sections well. In other cases, where several nucleons are emitted sequentially or in a cluster, the agreement is less satisfactory. (author)
Study of fusion probabilities with halo nuclei using different proximity based potentials
International Nuclear Information System (INIS)
Kumari, Raj
2013-01-01
We study fusion of halo nuclei with heavy targets using proximity based potentials due to Aage Winther (AW) 95, Bass 80 and Proximity 2010. In order to consider the extended matter distribution of halo nuclei, the nuclei radii borrowed from cross section measurements are included in these potentials. Our study reveals that the barrier heights are effectively reduced and fusion cross sections are appreciably enhanced by including extended radii of these nuclei. We also find that the extended sizes of halos contribute towards enhancement of fusion probabilities in case of proton halo nuclei, but, contribute to transfer or break-up process rather than fusion yield in case of neutron halo nuclei
Estimate of production of medical isotopes by photo-neutron reaction at the Canadian Light Source
Szpunar, B.; Rangacharyulu, C.; Daté, S.; Ejiri, H.
2013-11-01
In contrast to conventional bremsstrahlung photon beam sources, laser backscatter photon sources at electron synchrotrons provide the capability to selectively tune photons to energies of interest. This feature, coupled with the ubiquitous giant dipole resonance excitations of atomic nuclei, promises a fertile method of nuclear isotope production. In this article, we present the results of simulations of production of the medical/industrial isotopes 196Au, 192Ir and 99Mo by (γ,n) reactions. We employ FLUKA Monte Carlo code along with the simulated photon flux for a beamline at the Canadian Light Source in conjunction with a CO2 laser system.
Density functional theory of nuclei
International Nuclear Information System (INIS)
Terasaki, Jun
2008-01-01
The density functional theory of nuclei has come to draw attention of scientists in the field of nuclear structure because the theory is expected to provide reliable numerical data in wide range on the nuclear chart. This article is organized to present an overview of the theory to the people engaged in the theory of other fields as well as those people in the nuclear physics experiments. At first, the outline of the density functional theory widely used in the electronic systems (condensed matter, atoms, and molecules) was described starting from the Kohn-Sham equation derived on the variational principle. Then the theory used in the field of nuclear physics was presented. Hartree-Fock and Hartree-Fock-Bogolyubov approximation by using Skyrme interaction was explained. Comparison of the results of calculations and experiments of binding energies and ground state mean square charge radii of some magic number nuclei were shown. The similarity and dissimilarity between the two streams were summarized. Finally the activities of the international project of Universal Nuclear Energy Density Functional (UNEDF) which was started recently lead by US scientist was reported. This project is programmed for five years. One of the applications of the project is the calculation of the neutron capture cross section of nuclei on the r-process, which is absolutely necessary for the nucleosynthesis research. (S. Funahashi)
International Nuclear Information System (INIS)
Lozhkin, O.V.; Oplavin, V.S.; Yakovlev, Yu.P.
1983-01-01
The possibilities of search for 8 n 0 , 10 He 2 , 13 Li 3 nuclides in the products of nuclear fragmentation under the action of high energy particles are analysed. Conclusions have been drawn that: available experimental data on determination of the upper boundary of a cross section of 8 n 0 fragments production exclude an existence of this nuclide in the form ''usual'' nuclear system; available experimental estimations of cross sections of 10 He and 13 Li production among fragmentation products are, for the present, insufficient to solve a problem of 13 Li nucleus existence in a bound state but testify on 10 He nucleus nuclear instability; serious model estimations of have functions and nuclide binding energy are necessary
Derrickson, J. H.; Dake, S.; Dong, B. L.; Eby, P. B.; Fountain, W. F.; Fuki, M.; Gregory, J. C.; Hayashi, T.; Iyono, A.; King, D. T.
1989-01-01
Recently, new calculations were made of the direct Coulomb pair cross section that rely less in arbitrary parameters. More accurate calculations of the cross section down to low pair energies were made. New measurements of the total direct electron pair yield, and the energy and angular distribution of the electron pairs in emulsion were made for O-16 at 60 and 200 GeV/amu at S-32 at 200 GeV/amu which give satisfactory agreement with the new calculations. These calculations and measurements are presented along with previous accelerator measurements made of this effect during the last 40 years. The microscope scanning criteria used to identify the direct electron pairs is described. Prospects for application of the pair method to cosmic ray energy measurements in the region 10 (exp 13) to 10 (exp 15) eV/amu are discussed.
Microscopic structure for light nuclei
International Nuclear Information System (INIS)
Sharma, V.K.
1995-01-01
The microscopic structure for light nuclei e.g. 4 He, 7 Li and 8 Be is considered in the frame work of the generator coordinate method (GCM). The physical interpretation of our GCM is also discussed. The GC amplitudes are used to calculate the various properties like charge and magnetic RMS radii, form factors, electromagnetic moments, astrophysical S-factor, Bremsstrahlung weighted cross sections, relative wavefunctions and vertex functions etc. All the calculated quantities agree well with the values determined experimentally. (author). 30 refs., 10 figs., 2 tabs
Nucleus--nucleus total cross sections for light nuclei at 1.55 and 2.89 GeV/C/nucleon
International Nuclear Information System (INIS)
Jaros, J.A.
1975-11-01
Total cross sections have been measured for protons, deuterons, alphas, and 12 C on hydrogen, deuterium, helium, and carbon targets at 1.55 and 2.89 GeV/c/nucleon using the ''good geometry'' transmission method. In addition, the inelastic cross sections and elastic slope parameters were measured for reactions initiated by deuterons, alphas, and 12 C. The factorization relation sigma/sub T/(AA) = sigma/sub T/(AB) 2 /sigma/sub T/(BB) is violated for some of these reactions. The results generally agree with Glauber theory predictions except in their detailed energy behavior. It is found that sigma/sub T/ approximately equal to 144 (A/sub T//sup 1 / 3 / + A/sub P//sup 1 / 3 / - 1.48) 2 and sigma/sub IN/ approximately equal to 78 (A/sub T//sup 1 / 3 / + A/sub P//sup 1 / 3 / - 1.25) 2 , where A/sub T/(A/sub P/) is the atomic mass number of the target (projectile) and the cross sections are given in mb
International Nuclear Information System (INIS)
Guertin, A.
2001-01-01
A charged kaon includes a strange anti-quark that cannot be re-absorbed by matter which make kaons an interesting probe of nuclear matter. The first part of this work is dedicated to the production cross-sections of pions and kaons in proton-nucleus collision around 1 GeV. The molecular quantum dynamic model used for simulating proton-nucleus is presented and the total cross-sections of the reactions implemented in the model are described. Then, the impact of the neutron's spectral function on pion and kaon production is assessed in double differential cross-sections. The consequences of the correlations observed between nucleons are discussed. The simple phenomenological approach we have developed to take into account 2 nucleon correlations gives good results for the doubly differential production cross-section of pions and kaons whatever the target nucleus. The second part of this work is dedicated to the measurement of the production of light charged particles (p, d, t, "3He, α) and neutron production in collisions between 62,9 MeV protons with "2"0"8Pb nuclei. The experimental setting is installed on the S2 line of the CYCLONE cyclotron (Belgium), the detection system is composed of 7 triple telescopes (Si, Si and CsI(Tl)). The separation and identification of particles is made through 2 methods: the E-ΔE method based on the energy losses in the different detectors and the discrimination method based on the different shapes of the quick and slow signals of the CsI crystal. The extraction of the cross-section values is detailed. We have compared the values obtained with 3 theoretical models: the exciton model (GNASH code), the F.K.K. (Feshbach-Kerman-Koonin) theory (MINGUS code) and a more phenomenological model able to simulate hadron reactions on nuclei for a very broad range of energy (FLUKA code)
International Nuclear Information System (INIS)
El Zaiki, M.I.; Nafie, H.O.; Abd El Mageed, K.E.
1992-01-01
Two methods of calculations have been used to fit the previously presented data on rotationally aligned quasiparticle bands in sup(160,162,164,166)Yb. Backbendings of moment of inertia of the Yrast states can be reproduced reasonably well. The energy levels and the effective moment of inertia for both gs and s-band are calculated and compared with the experimental data. Band crossing interpretations are discussed for each nucleus. The interaction strength calculations are presented. (author). 17 refs., 7 figs., 4 tabs
International Nuclear Information System (INIS)
Grange, P.; Mathiot, J.F.; Roy-Stephan, M.; Frascaria, R.; Gales, S.
1990-01-01
The topics presented at the 1989 Joliot-Curie Lectures are reported. Two main subjects were retained: a simplified description of the N-body motion of particles in the quasi-particle configuration; study of the dynamics of nuclear components which are not described by nucleons in their ground state. The following themes were presented: quasiparticles and the Green functions, relativistic aspects of the quasiparticle concept, the dimensions of nucleons in the nuclei and the EMC effect, quarks and gluons in the nuclei, the delta in the nuclei, the strangeness, quasiparticles far from the Fermi sea, diffusion of electrons, stellar evolution and nucleosynthesis [fr
Dynamic polarisation of nuclei
International Nuclear Information System (INIS)
Borghini, M.; Abragam, A.
1961-01-01
In magnetic fields of about 13000 gauss, at a temperature of 1.5 deg. K, in samples of about 2 mm 3 , we have obtained by the 'solid effect' (application of a magnetic field at an appropriate frequency around 35000 MHz), nuclear polarizations /I of a few percent: 19 per cent for hydrogen nuclei in single crystals of La 2 Mg 3 (NO 3 ) 12 , 24H 2 O; 5 per cent for hydrogen nuclei in polystyrene; 6 per cent for fluorine nuclei in single crystals of LiF. (author) [fr
International Nuclear Information System (INIS)
Roberts, R.G.
1984-11-01
The paper concerns the behaviour of quarks in nuclei. Confinement size changes and dynamical rescaling; A dependence; low-x region; gluons and confinement size; and nucleons in a nucleus; are all discussed. (U.K.)
International Nuclear Information System (INIS)
Mackintosh, R.S.
1977-01-01
For the class of nuclei which are 'strongly deformed' it is possible to introduce the idea of an empirically measurable static nuclear shape. The limitations of this concept as applied to nuclei (fundamentally quantum-mechanical objects) are discussed. These are basically the limitations of the rotational model which must be introduced in order to define and measure nuclear shape. A unified discussion of the ways in which the shape has been parametrized is given with emphasis on the fact that different parametrizations correspond to different nuclear structures. Accounts of the various theoretical procedures for calculating nuclear shapes and of the interaction between nuclear shapes and nuclear spectroscopy are given. A coherent account of a large subset of nuclei (strongly deformed nuclei) can be given by means of a model in which the concept of nuclear shape plays a central role. (author)
International Nuclear Information System (INIS)
Aaberg, S.; Uhrenholt, H.
2009-01-01
We study the structure of nuclei in the energy region between the ground state and the neutron separation energy, here called warm nuclei. The onset of chaos in the nucleus as excitation energy is increased is briefly reviewed. Chaos implies fluctuations of energies and wave functions qualitatively the same for all chaotic nuclei. On the other hand, large structure effects are seen, e.g. in the level-density function at same excitation energies. A microscopic model for the level density is reviewed and we discuss effects on structure of the total level-density function, parity enhancement, and the spin distribution function. Comparisons to data are performed at the neutron separation energy for all observed nuclei, and structure of the level-density function for a few measured cases. The role of structure effects in the level-density function for fission dynamics is exemplified.
International Nuclear Information System (INIS)
Ismail, M.
1998-01-01
Excitation functions and a few isomeric cross section ratios for production of (1) 192 Au, 193 Au, 194 Au, 195 Au and 192 Ir nuclides in α-induced reactions on 191,193 Ir, (2) 197 Tl, 197m Hg, 198m.g Tl, 199 Tl and 200 Tl nuclides in α-induced reaction in 197 Au and (3) 183 Re and 184m.g Re nuclides in α-induced reaction in 181 Ta and 185 Re are obtained from the measurements of the residual activities by the conventional stacked-foils technique from threshold to 50 MeV. The excitation function and isomeric cross section ratios for nuclear reaction 181 Ta (α,n) 184m.g Re are compared with the theoretical calculation using the code Stapre which is based on exciton model for pre-equilibrium phase and Hauser-Feshbach formalism taking angular momentum and parity into account for the equilibrium phase of the nuclear reaction. All other experimental excitation functions are compared with the calculations considering equilibrium as well as pre-equilibrium reaction mechanism according to the geometry dependent hybrid (GDH) model and hybrid model of Blann using the code Alice/91. The high energy part of the excitation functions are dominated by pre-equilibrium reaction mechanism whereas the low energy parts are dominated by equilibrium evaporation with its characteristic peak. The GDH model provides a potentially better description of the physical process (i.e. a higher probability for peripheral collisions to undergo precompound decay than for central collisions) compared to hybrid model. However in the energy range of present measurement most of the excitation functions are fitted reasonably well by both GDH model and hybrid model with initial exciton number N 0 =4 (N n =2, N p =2, N h =0). Barring a few reactions we have found the overall agreement between theory and experiment is reasonably good taking the limitations of the theory into account. (author)
International Nuclear Information System (INIS)
Guerreau, D.
1993-01-01
A review is made of the present status concerning the production of nuclei above 5 MeV temperature. Considerable progress has been made recently on the understanding of the formation and the fate of such hot nuclei. It appears that the nucleus seems more stable against temperature than predicted by static calculations. However, the occurrence of multifragment production at high excitation energies is now well established. The various experimental features of the fragmentation process are discussed. (author) 59 refs., 12 figs
Juste, B.; Morató, S.; Miró, R.; Verdú, G.; Díez, S.
2017-08-01
Unwanted neutrons in radiation therapy treatments are typically generated by photonuclear reactions. High-energy beams emitted by medical Linear Accelerators (LinAcs) interact with high atomic number materials situated in the accelerator head and release neutrons. Since neutrons have a high relative biological effectiveness, even low neutron doses may imply significant exposure of patients. It is also important to study radioactivity induced by these photoneutrons when interacting with the different materials and components of the treatment head facility and the shielding room walls, since persons not present during irradiation (e.g. medical staff) may be exposed to them even when the accelerator is not operating. These problems are studied in this work in order to contribute to challenge the radiation protection in these treatment locations. The work has been performed by simulation using the latest state of the art of Monte-Carlo computer code MCNP6. To that, a detailed model of particles transport inside the bunker and treatment head has been carried out using a meshed geometry model. The LinAc studied is an Elekta Precise accelerator with a treatment photon energy of 15 MeV used at the Hospital Clinic Universitari de Valencia, Spain.
International Nuclear Information System (INIS)
Dale, Gregory E.; Gahl, John M.
2005-01-01
There are several potential uses for a high-flux thermal neutron source in both industrial and clinical applications. The viable commercial implementation of these applications requires a low-cost, high-flux thermal neutron generator suitable for installation in industrial and clinical environments. This paper describes the Monte Carlo for N-Particle modeling results of a high-flux thermal neutron source driven with an electron accelerator. An electron linear accelerator (linac), fitted with a standard X-ray converter, can produce high neutron yields in materials with low photonuclear threshold energies, such as D and 9 Be. Results indicate that a 10-MeV, 10-kW electron linac can produce on the order of 10 12 n/s in a heavy water photoneutron target. The thermal neutron flux in an unreflected heavy water target is calculated to be on the order of 10 10 n.cm -2 .s. The sensitivity of these answers to heavy water purity is also investigated, specifically the dilution of heavy water with light water. It is shown that the peak thermal neutron flux is not adversely effected by dilution up to a light water weight fraction of 35%
Symmetry energy, unstable nuclei and neutron star crusts
Energy Technology Data Exchange (ETDEWEB)
Iida, Kei [Kochi University, Department of Natural Science, Kochi (Japan); RIKEN Nishina Center, Saitama (Japan); Oyamatsu, Kazuhiro [RIKEN Nishina Center, Saitama (Japan); Aichi Shukutoku University, Department of Human Informatics, Aichi (Japan)
2014-02-15
The phenomenological approach to inhomogeneous nuclear matter is useful to describe fundamental properties of atomic nuclei and neutron star crusts in terms of the equation of state of uniform nuclear matter. We review a series of researches that we have developed by following this approach. We start with more than 200 equations of state that are consistent with empirical masses and charge radii of stable nuclei and then apply them to describe matter radii and masses of unstable nuclei, proton elastic scattering and total reaction cross sections off unstable nuclei, and nuclei in neutron star crusts including nuclear pasta. We finally discuss the possibility of constraining the density dependence of the symmetry energy from experiments on unstable nuclei and even observations of quasi-periodic oscillations in giant flares of soft gamma-ray repeaters. (orig.)
Nuclear-physical investigations with oriented nuclei and polarized neutrons
International Nuclear Information System (INIS)
Alfimenkov, V.P.; Pikel'ner, L.B.; Sharapov, Eh.I.
1980-01-01
Several experiments with oriented nuclei and polarized neutrons are considered, as well as some methods of polarization of neutrons and nuclei. Experiments on the study of spin dependence of neutron cross sections for fissionable and nonfissionable nuclei interaction of polarized neutrons with polarized nuclei as well as measurement of magnetic momenta of compound-states of rare-earth nuclei. Described are some investigations with thermal neutrons: study on spin dependence of neutron scattering length with nuclei and gamma radiation of neutron radiation capture. Difficulties of production of high-intensive polarized neutron beams and construction of oriented targets are noted. Neutron polarization by transmission of them through a polarized proton target is the most universal method (out of existing methods) in the energy range under consideration [ru
NESKA, Electron and Positron Scattering from Point Nuclei
International Nuclear Information System (INIS)
Idoeta, R.; Legarda, F.
2002-01-01
1 - Description of program or function: The Mott's differential cross section for the scattering of electrons and positrons by point nuclei without screening is calculated for any energy, atomic number and angle of scattering. 2 - Method of solution: We have summed the conditionally convergent series appearing in Mott's cross section using two consecutive transformations: the one of Yennie, Ravenhall and Wilson and that of Euler till we have seven times six significant figures repeated in the ratio of the Mott cross section to the classical Rutherford cross section. 3 - Restrictions on the complexity of the problem: Those appearing in the use of Mott's cross section for unscreened point nuclei
Monte Carlo approaches to light nuclei
International Nuclear Information System (INIS)
Carlson, J.
1990-01-01
Significant progress has been made recently in the application of Monte Carlo methods to the study of light nuclei. We review new Green's function Monte Carlo results for the alpha particle, Variational Monte Carlo studies of 16 O, and methods for low-energy scattering and transitions. Through these calculations, a coherent picture of the structure and electromagnetic properties of light nuclei has arisen. In particular, we examine the effect of the three-nucleon interaction and the importance of exchange currents in a variety of experimentally measured properties, including form factors and capture cross sections. 29 refs., 7 figs
Monte Carlo approaches to light nuclei
Energy Technology Data Exchange (ETDEWEB)
Carlson, J.
1990-01-01
Significant progress has been made recently in the application of Monte Carlo methods to the study of light nuclei. We review new Green's function Monte Carlo results for the alpha particle, Variational Monte Carlo studies of {sup 16}O, and methods for low-energy scattering and transitions. Through these calculations, a coherent picture of the structure and electromagnetic properties of light nuclei has arisen. In particular, we examine the effect of the three-nucleon interaction and the importance of exchange currents in a variety of experimentally measured properties, including form factors and capture cross sections. 29 refs., 7 figs.
Maris polarization in neutron-rich nuclei
Shubhchintak; Bertulani, C. A.; Aumann, T.
2018-03-01
We present a theoretical study of the Maris polarization effect and its application in quasi-free reactions to assess information on the structure of exotic nuclei. In particular, we explore the dependence of the polarization effect on neutron excess and neutron-skin thickness. We discuss the uncertainties in the calculations of triple differential cross sections and of analyzing powers due the choices of various nucleon-nucleon interactions and optical potentials and the limitations of the method. Our study implies that polarization variables in (p, 2p) reactions in inverse kinematics can be an effective probe of single-particle structure of nuclei in radioactive-beam facilities.
New aspects of the neutron capture in light nuclei
Energy Technology Data Exchange (ETDEWEB)
Mengoni, A. [Institute of Physical and Chemical Research, Wako, Saitama (Japan)
1997-03-01
Several neutron capture cross sections of light nuclei (A {<=} 40) for neutron energies up to the MeV region have been recently calculated. Examples are (target nuclei): {sup 12}C, {sup 13}C, {sup 16}O and {sup 10}Be. The results of these calculations will be shown together with a comparison with the most recent experimental data. In the case of n + {sup 10}Be case, the cross section of the inverse process (Coulomb dissociation of {sup 11}Be) is considered and compared with the measurement. A discussion on the relevant nuclear structure information required for the evaluation of nuclear data of light nuclei is given. (author)
Multifragmentation of hot nuclei
International Nuclear Information System (INIS)
Tamain, B.
1990-10-01
It is difficult to deposit a large amount (∼ 1 Gev) of excitation energy into a nucleus. And if one wants to deposit large excitation energy values, the best way consists of shooting a given target nucleus with several nucleons, which can be achieved by using intermediate energy (10-100 MeV/nucleon) heavy ions. Such very excited objects were named hot nuclei. The study of hot nuclei has been undertaken only for 7 years because intermediate energy heavy ion facilities were not available before. The game is then to determine the decay properties of such nuclei, their limits of existence. Their study is connected with general properties of nuclear matter: namely its equation of state. Of special interest, is the onset of a new decay mechanism: multifragmentation, which is the non-sequential disassembly of a hot nucleus into several light nuclei (often called intermediate-mass fragments or IMF) or particles. This paper, shows how this mechanism can reflect fundamental properties of nuclear matter, but also how its experimental signature is difficult to establish. Multifragmentation has also been studied by using very energetic projectiles (protons and heavy ions) in the relativistic or ultra-relativistic region. The multifragmentation question of hot nuclei is far from being solved. One knows that IMF production increases when the excitation energy brought into a system is strongly increased, but very little is known about the mechanisms involved and a clear onset for multifragmentation is not established
International Nuclear Information System (INIS)
Schramm, D.N.
1995-01-01
Primordial nucleosynthesis has established itself as one of the three pillars of Big Bang cosmology. Many of the Big Bang Nucleosynthesis reactions involve unstable nuclei. Hence there is a tight relationship hetween the subject of this conference and cosmology. The prime role of unstable nuclei in cosmology is related to lithium synthesis and the lack of cosmological synthesis of Be and B. These nuclei will thus be focused upon. Nucleosynthesis involves comparing calculated abundances with observed abundances. In general, abundance determinations are dominated by systematic rather than statistical errors, and work on bounding systematics is crucial. The quark-hadron inspired inhomogeneous calculations now unanimously agree that only relatively small variations in Ω b are possible vis-a-vis the homogeneous model; hence the robustness of Ω b ∼0.05 is now apparent. (These calculations depend critically on unstable nuclei.) The above argues that the bulk of the baryons in the universe are not producing visible light. A comparison with the ROSAT cluster data is also shown to be consistent with the standard BBN model. Ω b ∼1 seems to be definitely excluded, so if Ω TOTAL =1, as some recent observations may hint, then non-baryonic dark matter is required. The implications of the recently reported halo microlensing events are discussed. In summary, it is argued that the physics of unstable nuclei affects the fundamental dark matter argument. ((orig.))
International Nuclear Information System (INIS)
Yuecel, Haluk; Kolbasi, Asuman; Yueksel, Alptug Oezer; Cobanbas, Ibrahim; Kaya, Vildan
2016-01-01
High-energy linear accelerators are increasingly used in the medical field. However, the unwanted photo-neutrons can also be contributed to the dose delivered to the patients during their treatments. In this study, neutron fluxes were measured in a solid water phantom placed at the isocenter 1-m distance from the head of an 18-MV linac using the foil activation method. The produced activities were measured with a calibrated well-type Ge detector. From the measured fluxes, the total neutron fluence was found to be (1.17 ± 0.06) X 10 7 n/cm 2 per Gy at the phantom surface in a 20 X 20 cm 2 X-ray field size. The maximum photo-neutron dose was measured to be 0.67 ± 0.04 mSv/Gy at d max = 5 cm depth in the phantom at isocenter. The present results are compared with those obtained for different field sizes of 10 X 10cm 2 , 15 X 15cm 2 , and 20 X 20cm 2 from 10-, 15-, and 18-MV linacs. Additionally, ambient neutron dose equivalents were determined at different locations in the room and they were found to be negligibly low. The results indicate that the photo-neutron dose at the patient position is not a negligible fraction of the therapeutic photon dose. Thus, there is a need for reduction of the contaminated neutron dose by taking some additional measures, for instance, neutron absorbing-protective materials might be used as aprons during the treatment
International Nuclear Information System (INIS)
Clark, R.M.
2004-01-01
It has been suggested that a change of nuclear shape may be described in terms of a phase transition and that specific nuclei may lie close to the critical point of the transition. Analytical descriptions of such critical-point nuclei have been introduced recently and they are described briefly. The results of extensive searches for possible examples of critical-point behavior are presented. Alternative pictures, such as describing bands in the candidate nuclei using simple ΔK = 0 and ΔK = 2 rotational-coupling models, are discussed, and the limitations of the different approaches highlighted. A possible critical-point description of the transition from a vibrational to rotational pairing phase is suggested
Fundamental Physics with Electroweak Probes of Nuclei
Pastore, Saori
2018-02-01
The past decade has witnessed tremendous progress in the theoretical and computational tools that produce our understanding of nuclei. A number of microscopic calculations of nuclear electroweak structure and reactions have successfully explained the available experimental data, yielding a complex picture of the way nuclei interact with electroweak probes. This achievement is of great interest from the pure nuclear-physics point of view. But it is of much broader interest too, because the level of accuracy and confidence reached by these calculations opens up the concrete possibility of using nuclei to address open questions in other sub-fields of physics, such as, understanding the fundamental properties of neutrinos, or the particle nature of dark matter. In this talk, I will review recent progress in microscopic calculations of electroweak properties of light nuclei, including electromagnetic moments, form factors and transitions in between lowlying nuclear states along with preliminary studies for single- and double-beta decay rates. I will illustrate the key dynamical features required to explain the available experimental data, and, if time permits, present a novel framework to calculate neutrino-nucleus cross sections for A > 12 nuclei.
International Nuclear Information System (INIS)
Walecka, J.D.
1983-01-01
Nuclei provide systems where the strong, electomagnetic, and weak interactions are all present. The current picture of the strong interactions is based on quarks and quantum chromodynamics (QCD). The symmetry structure of this theory is SU(3)/sub C/ x SU(2)/sub W/ x U(1)/sub W/. The electroweak interactions in nuclei can be used to probe this structure. Semileptonic weak interactions are considered. The processes under consideration include beta decay, neutrino scattering and weak neutral-current interactions. The starting point in the analysis is the effective Lagrangian of the Standard Model
International Nuclear Information System (INIS)
Rho, M.; CEA Centre d'Etudes Nucleaires de Saclay, 91 - Gif-sur-Yvette
1983-01-01
Some features of quark degrees of freedom in nuclei are discussed in the light of recent developments in QCD. The principal aim of this talk is to propose, and give a tentative support to, the motion that one can study through nuclear matter different facets of the vacuum structure implied by quantum chromodynamics (QCD). This will be done using the recent (exciting) results obtained in particle physics, in particular lattice gauge calculations. Relevance of this aspect of problem to quark degrees of freedom as well as meson degrees of freedom in nuclei will be discussed. (orig.)
Disintegration of comet nuclei
Ksanfomality, Leonid V.
2012-02-01
The breaking up of comets into separate pieces, each with its own tail, was seen many times by astronomers of the past. The phenomenon was in sharp contrast to the idea of the eternal and unchangeable celestial firmament and was commonly believed to be an omen of impending disaster, especially for comets with tails stretching across half the sky. It is only now that we have efficient enough space exploration tools to see comet nuclei and even - in the particular case of small comet Hartley-2 in 2010 - to watch their disintegration stage. There are also other suspected candidates for disintegration in the vast family of comet nuclei and other Solar System bodies.
International Nuclear Information System (INIS)
2002-01-01
The present collection of letters from JINR, Dubna, contains seven separate records on kinematic separation and mass analysis of heavy recoiling nuclei, dynamical effects prior to heavy ion fusion, VACTIV-DELPHI graphical dialog based program for the analysis of gamma-ray spectra, irradiation of nuclear emulsions in relativistic beams of 6 He and 3 H nuclei, optical and structural investigations of PLZT x/65/35 (x = 4, 8 %) ferroelectric ceramics irradiated by a high-current pulsed electron beam, the oscillating charge and first evidence for neutrinoless double beta decay
International Nuclear Information System (INIS)
2001-01-01
The present collection of letters from JINR, Dubna, contains seven separate records on physics from extra dimensions, new physics in the new millennium with GENIUS: double beta decay, dark matter, solar neutrinos, the (μ - , e + ) conversion in nuclei mediated by light Majorana neutrinos, exotic muon-to-positron conversion in nuclei: partial transition sum evaluation by using shell model, solar neutrino problem accounting for self consistent magnetohydrodynamics solution for solar magnetic fields, first neutrino observations from the Sudbury neutrino observatory and status report on BOREXINO and results of the muon-background measurements at CERN
International Nuclear Information System (INIS)
Bohr, A.
1976-01-01
Nuclear structure theories are reviewed concerned with nuclei rotational motion. The development of the deformed nucleus model facilitated a discovery of rotational spectra of nuclei. Comprehensive verification of the rotational scheme and a successful classification of corresponding spectra stimulated investigations of the rotational movement dynamics. Values of nuclear moments of inertia proved to fall between two marginal values corresponding to rotation of a solid and hydrodynamic pattern of an unrotating flow, respectively. The discovery of governing role of the deformation and a degree of a symmetry violence for determining rotational degrees of freedon is pointed out to pave the way for generalization of the rotational spectra
Deformation and shape coexistence in medium mass nuclei
International Nuclear Information System (INIS)
Meyer, R.A.
1985-01-01
Emerging evidence for deformed structures in medium mass nuclei is reviewed. Included in this review are both nuclei that are ground state symmetric rotors and vibrational nuclei where there are deformed structures at excited energies (shape coexistence). For the first time, Nilsson configurations in odd-odd nuclei within the region of deformation are identified. Shape coexistence in nuclei that abut the medium mass region of deformation is also examined. Recent establishment of a four-particle, four-hole intruder band in the double subshell closure nucleus 96 Zr 56 is presented and its relation to the nuclear vibron model is discussed. Special attention is given to the N=59 nuclei where new data have led to the reanalysis of 97 Sr and 99 Zr and the presence of the [404 9/2] hole intruder state as isomers in these nuclei. The low energy levels of the N=59 nuclei from Z=38 to 50 are compared with recent quadrupole-phonon model calculations that can describe their transition from near-rotational to single closed shell nuclei. The odd-odd N=59 nuclei are discussed in the context of coexisting shape isomers based on the (p[303 5/2]n[404 9/2])2 - configuration. Ongoing in-beam (t,p conversion-electron) multiparameter measurements that have led to the determination of monopole matrix elements for even-even 42 Mo nuclei are presented, and these are compared with initial estimates using IBA-2 calculations that allow mixing of normal and cross subshell excitations. Lastly, evidence for the neutron-proton 3 S 1 force's influence on the level structure of these nuclei is discussed within the context of recent quadrupole-phonon model calculations. (Auth.)
International Nuclear Information System (INIS)
Henley, E.M.
1987-01-01
Nuclei are very useful for testing symmetries, and for studies of symmetry breaking. This thesis is illustrated for two improper space-time transformations, parity and time-reversal and for one internal symmetry: charge symmetry and independence. Recent progress and present interest is reviewed. 23 refs., 8 figs., 2 tabs
Electroweak interactions in nuclei
International Nuclear Information System (INIS)
Henley, E.M.
1984-06-01
Topics include: introduction to electroweak theory; the Weinberg-Salam theory for leptons; the Weinberg-Salam theory for hadrons-the GIM mechanism; electron scattering as a probe of the electroweak interaction (observation of PV, the weak interaction for nucleons, and parity violation in atoms); and time reversed invariance and electric dipole moments of nucleons, nuclei, and atoms. 52 references
Transfer involving deformed nuclei
International Nuclear Information System (INIS)
Rasmussen, J.O.; Guidry, M.W.; Canto, L.F.
1985-03-01
Results are reviewed of 1- and 2-neutron transfer reactions at near-barrier energies for deformed nuclei. Rotational angular momentum and excitation patterns are examined. A strong tendency to populating high spin states within a few MeV of the yrast line is noted, and it is interpreted as preferential transfer to rotation-aligned states. 16 refs., 12 figs
International Nuclear Information System (INIS)
Gulamov, K.G.
1987-01-01
It is well known that interactions of high energy particles with nuclei, owing to possible intranuclear rescatterings, may provide information about the space-time behaviour of the production process. Therefore the main goals of these investigations are related with the attempts to study the space-time process of hadronization of coloured quarks and gluons produced at the initial stage of an interaction to white final state particles and to clarify the influence of composite quark-gluon structure of both the projectile and target on features of the production mechanisms. Since in both the initial and final states of these reactions the authors have strongly interacting multiparticle systems, it is of importance to study the collective properties of these systems. The questions to the point are: what is the degree of collectivization of particles newly produced in collisions with nuclei and what is the influence of the collective nature of a nucleus itself on the production mechanisms, in particular, what are the manifestations of possible multinucleon (multiquark) configurations in nuclei? It is obvious that the reductability of, say, hadron-nucleus (hA) interaction to hadron-nucleon (hN) collisions is directly related to the above problems. Due to time limitations the author discusses here only a few aspects of low p/sub t/ hA interactions which in his opinion are of importance for better understanding of general regularities of collisions with nuclei and for further investigations of the above problems
International Nuclear Information System (INIS)
Laget, J.M.
1988-01-01
This summary is a review of our understanding of nuclei in terms of hadrons exchanging mesons. The open problems are: the determination of the high momentum components of nuclear systems, the role of the three-body forces and the nature of the short range correlations. The ways of studying these problems are discussed
Electromagnetic structure of nuclei
International Nuclear Information System (INIS)
Arnold, R.G.
1986-07-01
A brief review is given of selected topics in the electromagnetic structure of nucleons and nuclei, including nucleon form factors from both quantum chromodynamics and electron scattering data, measurements of the deuteron and triton form factors, quasi-elastic scattering, and the EMC effect. 47 refs., 13 figs
International Nuclear Information System (INIS)
Bohr, A.
1977-01-01
History is surveyed of the development of the theory of rotational states in nuclei. The situation in the 40's when ideas formed of the collective states of a nucleus is evoked. The general rotation theory and the relation between the single-particle and rotational motion are briefly discussed. Future prospects of the rotation theory development are indicated. (I.W.)
International Nuclear Information System (INIS)
Truhlik, E.; Mach, R.
1992-01-01
62 papers and one summary talk were presented at the conference, on subject matters in between nuclear physics (mainly light nuclei) and elementary particle physics, as indicated by the session headings (1) Electroweak nuclear interaction (2) Nuclear physics with pions and antiprotons (3) Nuclear physics with strange particles (4) Relativistic nuclear physics (5) Quark degrees of freedom. (Quittner)
International Nuclear Information System (INIS)
Hodgson, P.E.
1990-01-01
The effects of nucleon clustering in nuclei are described, with reference to both nuclear structure and nuclear reactions, and the advantages of using the cluster formalism to describe a range of phenomena are discussed. It is shown that bound and scattering alpha-particle states can be described in a unified way using an energy-dependent alpha-nucleus potential. (author)
International Nuclear Information System (INIS)
Harris, J.
1986-01-01
The book on particles, imaging and nuclei is one of the Background Readers for the Revised Nuffield Advanced Physics course. The contents contain five educational articles, which extend concepts covered in the course and examine recent developments in physics. Four of the articles on:- particles and the forces of nature, radioisotopes, lasers probe the atomic nucleus, and nuclear history, are indexed separately. (UK)
International Nuclear Information System (INIS)
Bitsadze, G.S.; Budagov, Yu.A.; Dzhelepov, V.P.
1986-01-01
The results of the study of π + n → K + Σ 0 and π + n → K + Λ reactions at 10.3 GeB/c are presented. The measurements were carried out at missing mass spectrometer HYPERON at IHEP accelerator. The differential cross sections in 0 ≤ t-t min 2 momentum transfer range are measured. The integral cross sections in the studied t-interval are (11.8±1.1)μb and (21.7±2.2)μb for reactions π + n → K + Σ 0 and π + n → K + Λ, respectively. The obtained results were compared with the predictions of quasi-eikonal model and with other experimental data. The ratio A eff (t) of differential cross sections for π + A → K + Y+A' reactions on carbon and deuterium nuclei are measured. The A cff (t) tend to grow with increasing t in agreement with the predictions of QCD-based model
International Nuclear Information System (INIS)
Moretto, L.G.; Wozniak, G.J.
1988-11-01
The formation of hot compound nuclei in intermediate-energy heavy ion reactions is discussed. The statistical decay of such compound nuclei is responsible for the abundant emission of complex fragments and high energy gamma rays. 43 refs., 23 figs
Isotope shifts in unstable nuclei
International Nuclear Information System (INIS)
Rebel, H.
1980-05-01
Current experimental investigations of isotope shifts in atomic spectra of unstable nuclei and the resulting information about size and shape of nuclei far off stability are discussed with reference to some representative examples. (orig.)
Energetic Nuclei, Superdensity and Biomedicine
Baldin, A. M.
1977-01-01
High-energy, relativistic nuclei were first observed in cosmic rays. Studing these nuclei has provided an opportunity for analyzing the composition of cosmic rays and for experimentally verifying principles governing the behavior of nuclear matter at high and super-high temperatures. Medical research using accelerated nuclei is suggested.…
Particle-rotation coupling in atomic nuclei
International Nuclear Information System (INIS)
Almberger, J.
1980-01-01
Recently an increased interest in the rotational nuclei has been spurred by the new experimental high-spin activities and by the possibilities for lower spins to interpret an impressive amount of experimental data by some comparatively simple model calculations. The author discusses the particle modes of excitation for rotational nuclei in the pairing regime where some puzzles in the theoretical description remain to be resolved. A model comparison is made between the particle-rotor and cranking models which have different definitions of the collective rotation. The cranking model is found to imply a smaller value of the quasiparticle spin alignment than the particle-rotor model. Rotational spectra for both even and odd nuclei are investigated with the use of the many-BCS-quasiparticles plus rotor model. This model gives an accurate description of the ground and S-bands in many even-even rare-earth nuclei. However, the discrepancies for odd-A nuclei between theory and experiments point to the importance of additional physical components. Therefore the rotationally induced quadrupole pair field is considered. This field has an effect on the low spin states in odd-A nuclei, but is not sufficient to account for the experimental data. Another topic considered is the interaction matrix element in crossings for given spin between quasiparticle rotational bands. The matrix elements are found to oscillate as a function of the number of particles, thereby influencing the sharpness of the backbending. Finally the low-spin continuation of the S-band is studied and it is shown that such states can be populated selectively by means of one-particle pickup reactions involving high angular momentum transfer. (Auth.)
Disintegration of comet nuclei
International Nuclear Information System (INIS)
Ksanfomality, Leonid V
2012-01-01
The breaking up of comets into separate pieces, each with its own tail, was seen many times by astronomers of the past. The phenomenon was in sharp contrast to the idea of the eternal and unchangeable celestial firmament and was commonly believed to be an omen of impending disaster, especially for comets with tails stretching across half the sky. It is only now that we have efficient enough space exploration tools to see comet nuclei and even - in the particular case of small comet Hartley-2 in 2010 - to watch their disintegration stage. There are also other suspected candidates for disintegration in the vast family of comet nuclei and other Solar System bodies. (physics of our days)
International Nuclear Information System (INIS)
Huefner, J.
1975-01-01
Are pions a good tool to study nuclei. If the emphasis of this question rests on ''tool'', the answer must be ''not yet.'' The reason: one does not even understand how a pion interacts with a nucleus. This is part of the many-body problem for strongly interacting particles and its study is a basic problem in physics. One must investigate questions like: Can one understand pion-nucleus interactions from pion-nucleon physics. How does a Δ-resonance look in nuclei. Once one has solved those basic problems, there will be spinoffs in medical, technical and nuclear areas. Then pions can be used as a tool to study nuclear properties
International Nuclear Information System (INIS)
Whelan, N.D.
1993-01-01
Random Matrix Theory successfully describes the statistics of the low-lying spectra of some nuclei but not of others. It is currently believed that this theory applies to systems in which the corresponding classical motion is chaotic. This conjecture is tested for collective nuclei by studying the Interacting Boson Model. Quantum and classical measures of chaos are proposed and found to be in agreement throughout the parameter space of the model. For some parameter values the measures indicate the presence of a previously unknown approximate symmetry. A phenomenon called partial dynamical symmetry is explored and shown to lead to a suppression of chaos. A time dependent function calculated from the quantum spectrum is discussed. This function is sensitive to the extent of chaos and provides a robust method of analyzing experimental spectra
International Nuclear Information System (INIS)
Mitchel, G.; Shriner, J.
2005-01-01
Although the predictions of Random Matrix Theory (RMT) were available by the early 1960s, data of sufficiently high quality to adequately test the theory were only obtained a decade later by Rainwater. It was another decade later that Bohigas, Haq and Pandey combined the best available nuclear resonance data - the Columbia neutron resonances in heavy nuclei and the TUNL proton resonances in lighter nuclei - to form the Nuclear Data Ensemble. They obtained excellent agreement for the level statistics with the RMT predictions. The expected Porter-Thomas (PT) distribution was considered very early. However, since the widths (amplitudes squared) are measured, the predicted Gaussian distribution for the amplitudes was only qualitatively confirmed. A much more sensitive test was performed by measuring two widths and the relative phase between the two amplitudes. By comparison of the width and amplitude correlations, the Gaussian distribution was confirmed at the 1% level. Following the Bohigas conjecture - that quantum analogs of classically chaotic systems obey RMT - there was an explosion of activity utilizing level statistics in many different quantum systems. In nuclei the focus was verifying the range of applicability of RMT. Of particular interest was the effect of collectivity and of excitation energy on statistical properties. The effect of symmetry breaking on level statistics was examined and early predictions by Dyson were confirmed. The effect of symmetry breaking on the width distribution was also measured for the first time. Although heuristic arguments predicted no change from the PT distribution, experimentally there was a large deviation from the PT prediction. Later theoretical efforts were consistent with this result. The stringent conditions placed on the experiments - for eigenvalue tests the data need to be essentially perfect (few or no missing levels or mis assigned quantum numbers) - has limited the amount of suitable experimental data. The
Energy Technology Data Exchange (ETDEWEB)
Khouaja, A
2003-12-01
Using the direct method, the mean energy integrated reaction cross section was investigated for a wide range of neutron-rich nuclei (N {yields} Ar) at GANIL. Using the parametrisation of S. Kox, 19 new radii measurements (reaction cross sections) were obtained. By the isotopic, isotonic and isospin dependence, the evolution of the strong reduced radius was studied according to the excess of neutrons. New halo effect is proposed to the nuclei of Mg{sup 35} and S{sup 44}. A quadratic parametrization is also proposed for the nuclear radius as a function of the isospin in the region of closed shells N=8 and N=28. In addition, we used a modified version of the Glauber model for studying the tail and matter distribution of nuclei. Indeed, using our new data the effects of the nuclear size (root mean square radii) and the matter distribution (diffusivity) were de-convoluted for each isotope. The root mean square radii of Na and Mg isotopes obtained so far were consistent with the ones from literature. (author)
International Nuclear Information System (INIS)
Hamilton, J.H.
1987-01-01
Discoveries of many different types of nuclear shape coexistence are being found at both low and high excitation energies throughout the periodic table, as documented in recent reviews. Many new types of shape coexistence have been observed at low excitation energies, for examples bands on more than four different overlapping and coexisting shapes are observed in 185 Au, and competing triaxial and prolate shapes in 71 Se and 176 Pt. Discrete states in super-deformed bands with deformations β 2 ∼ 0.4-0.6, coexisting with other shapes, have been seen to high spin up to 60ℎ in 152 Dy, 132 Ce and 135 Nd. Super-deformed nuclei with N and Z both around 38 and around Z = 38, N ≥ 60. These data led to the discovery of new shell gaps and magic numbers of 38 for N and Z and 60 for N but now for deformed shapes. Marked differences in structure are observed at spins of 6 to 20 in nuclei in this region, which differ by only two protons; for example, 68 Ge and 70 Se. The differences are thought to be related to the competing shell gaps in these nuclei
Elusive active galactic nuclei
Maiolino, R.; Comastri, A.; Gilli, R.; Nagar, N. M.; Bianchi, S.; Böker, T.; Colbert, E.; Krabbe, A.; Marconi, A.; Matt, G.; Salvati, M.
2003-10-01
A fraction of active galactic nuclei do not show the classical Seyfert-type signatures in their optical spectra, i.e. they are optically `elusive'. X-ray observations are an optimal tool to identify this class of objects. We combine new Chandra observations with archival X-ray data in order to obtain a first estimate of the fraction of elusive active galactic nuclei (AGN) in local galaxies and to constrain their nature. Our results suggest that elusive AGN have a local density comparable to or even higher than optically classified Seyfert nuclei. Most elusive AGN are heavily absorbed in the X-rays, with gas column densities exceeding 1024 cm-2, suggesting that their peculiar nature is associated with obscuration. It is likely that in elusive AGN the nuclear UV source is completely embedded and the ionizing photons cannot escape, which prevents the formation of a classical narrow-line region. Elusive AGN may contribute significantly to the 30-keV bump of the X-ray background.
On deuteron break-up at interaction with heavy nuclei
International Nuclear Information System (INIS)
Evlanov, M.V.; Nemets, O.F.; Struzhko, B.G.
1975-01-01
The aim of the paper is the study of the nuclear boundary diffusivity during disintegration of a deutron on heavy nuclei for various combinations of neutron and proton emission angles. The formulae has obtained for the cross section and the amplitude of nuclear interaction. The calculation of angular correlations between emission directions of deutron disintegration products and energy spectra of released protons depending on the nuclear boundary diffusivity is made. It is shown that the differential cross sections of deutron fission disintegration decrease with increasing nuclear boundary diffusivity. This effect may serve a qualitative explanation for observed differences in the deutron disintegration cross sections on heavy nuclei
Calculation of the radii of neutron rich light exotic nuclei
International Nuclear Information System (INIS)
Charagi, S.K.; Gupta, S.K.
1991-01-01
The interaction cross section of a few unstable neutron rich nuclei have been measured using exotic isotope beams produced through the projectile fragmentation process in high energy heavy-ion collisions. Interaction cross section of He, Li, Be and B isotope projectiles with Be, C and Al targets have thus been measured at 790 MeV/nucleon. We have made a comprehensive analysis of the data on the interaction cross section, to extract the radii of these neutron rich light nuclei. 7 refs., 1 fig., 3 tabs
The intergalactic propagation of ultrahigh energy cosmic ray nuclei
Energy Technology Data Exchange (ETDEWEB)
Hooper, Dan; /Fermilab; Sarkar, Subir; /Oxford U., Theor. Phys.; Taylor, Andrew M.; /Oxford U.
2006-08-01
We investigate the propagation of ultra-high energy cosmic ray nuclei (A = 1-56) from cosmologically distant sources through the cosmic radiation backgrounds. Various models for the injected composition and spectrum and of the cosmic infrared background are studied using updated photodisintegration cross-sections. The observational data on the spectrum and the composition of ultra-high energy cosmic rays are jointly consistent with a model where all of the injected primary cosmic rays are iron nuclei (or a mixture of heavy and light nuclei).
Relativistic mean field calculations in neutron-rich nuclei
Energy Technology Data Exchange (ETDEWEB)
Gangopadhyay, G.; Bhattacharya, Madhubrata [Department of Physics, University of Calcutta, 92 Acharya Prafulla Chandra Road, Kolkata 700 009 (India); Roy, Subinit [Saha Institute of Nuclear Physics, Block AF, Sector 1, Kolkata- 700 064 (India)
2014-08-14
Relativistic mean field calculations have been employed to study neutron rich nuclei. The Lagrange's equations have been solved in the co-ordinate space. The effect of the continuum has been effectively taken into account through the method of resonant continuum. It is found that BCS approximation performs as well as a more involved Relativistic Continuum Hartree Bogoliubov approach. Calculations reveal the possibility of modification of magic numbers in neutron rich nuclei. Calculation for low energy proton scattering cross sections shows that the present approach reproduces the density in very light neutron rich nuclei.
Energy spectra of odd nuclei in the generalized model
Directory of Open Access Journals (Sweden)
I. O. Korzh
2015-04-01
Full Text Available Based on the generalized nuclear model, energy spectra of the odd nuclei of such elements as 25Mg, 41K, and 65Cu are determined, and the structure of wave functions of these nuclei in the excited and normal states is studied. High quality in determining the energy spectra is possible due to the accurate calculations of all elements of the energy matrix. It is demonstrated that the structure of the wave functions so determined provides the possibility to more accurately select the nuclear model and the method for calculating the nucleon cross-sections of the inelastic scattering of nucleons by odd nuclei.
Introduction to the study of collisions between heavy nuclei
International Nuclear Information System (INIS)
Bayman, B.F.
1980-01-01
Current investigations concerning the collisions of nuclei governed by small de Broglie wavelengths are reviewed. The wave packets localize nuclei in regions small compared to their diameters. Cross sections are examined for potential scattering, elastic scattering, quasi-molecular states, peripheral particle-transfer reactions, fusion, and deep inelastic collisions. Theories of fusion and deep inelastic collisions are summarized. This paper is in the nature of a review-tutorial. 45 references, 51 figures, 2 tables
Absolute measurements of neutron cross sections. Progress report
International Nuclear Information System (INIS)
1984-11-01
In the photoneutron laboratory, we have completed a major refurbishing of experimental facilities and begun work on measurements of the capture cross section in thorium and U-238. In the 14 MeV neutron experimental bay, work continues on the measurement of 14 MeV neutron induced reactions of interest as standards or because of their technological importance. First results have been obtained over the past year, and we are extending these measurements along the lines outlined in our proposal of a year ago
International Nuclear Information System (INIS)
Geissel, H.
1997-03-01
Examinations of the production cross-sections and the kinematics permitted refinement of model concepts of the peripheral reactions in exotic nuclei at energies from 100 to 1000 A MeV. Due to the strong selectivity and resolution achieved it was possible to discover a large number of novel isotopes at the fragment separator FRS, despite the relatively low projectile beam intensities of the SIS. The two twice magic nuclei found, Ni 78 and Sn 100, are particularly interesting, as they could not be measured so far with other experimental systems. Fission of relativistic uranium ions proved to be a particularly successful process yielding many medium-heavy, neutron-rich nuclei. Insight into the structure of light neutron halos could be improved. The superlarge spatial dimensions of the nuclear halos is discussed. (orig./CB) [de
Structure functions of nucleons and nuclei
Energy Technology Data Exchange (ETDEWEB)
Bentz, Wolfgang; Ito, Takuya [Department of Physics, Tokai University, Kanagawa (Japan); Cloet, Ian [Department of Physics, University of Washington, Seattle (United States); Thomas, Anthony [Jefferson Lab., Newport News, VA (United States); Yazaki, Koichi [RIKEN, Wako-shi, Saitama (Japan)
2009-07-01
We use an effective chiral quark theory to calculate the quark distributions and structure functions of nucleons and nuclei. The description of the single nucleon is based on the Faddeev framework, and nuclear systems are described in the mean field approximation. Particular amphasis is put on the prediction of the polarized EMC effect in nuclei, and on applications to deep inelastic neutrino-nucleus scattering. Concerning the polarized EMC effect, we discuss the quenching of the quark spin sum in nuclei and its implications for the spin dependent nuclear structure functions, and present results for several nuclei where an experimental observation is feasible. Concerning the case of deep inelastic neutrino-nucleus scattering, we estimate the effect of medium modifications of the quark distribution functions on the measured cross sections, and discuss an interesting resolution of the so called NuTeV anomaly. Finally, we discuss extensions of our model to describe fragmentation functions for semi-inclusive processes. The connection between our effective quark model description and the jet model of Field and Feynman is discussed.
Shell model calculations for exotic nuclei
International Nuclear Information System (INIS)
Brown, B.A.; Wildenthal, B.H.
1991-01-01
A review of the shell-model approach to understanding the properties of light exotic nuclei is given. Binding energies including p and p-sd model spaces and sd and sd-pf model spaces; cross-shell excitations around 32 Mg, including weak-coupling aspects and mechanisms for lowering the ntw excitations; beta decay properties of neutron-rich sd model, of p-sd and sd-pf model spaces, of proton-rich sd model space; coulomb break-up cross sections are discussed. (G.P.) 76 refs.; 12 figs
Sub-Coulomb fusion with halo nuclei
International Nuclear Information System (INIS)
Fekou-Youmbi, V.; Sida, J.L.; Alamanos, N.; Auger, F.; Bazin, D.; Borcea, C.; Cabot, C.; Cunsolo, A.; Foti, A.; Gillibert, A.; Lepine, A.; Lewitowicz, M.; Liguori-Neto, R.; Mittig, W.; Pollacco, E.; Roussel-Chomaz, P.; Volant, C.; Yong Feng, Y.
1995-01-01
The nuclear structure of halo nuclei may have strong influence on the fusion cross section at sub-barrier energies. The actual theoretical debate is briefly reviewed and sub-barrier fusion calculations for the system 11 Be+ 238 U are presented. An experimental program on sub-barrier fusion for the systems 7,9,10,11 Be+ 238 U is underway at GANIL. First results with 9 Be and 11 Be beams were obtained using the F.U.S.ION detector. Relative fission cross sections are presented. ((orig.))
Photofissility of heavy nuclei at intermediate energies
International Nuclear Information System (INIS)
Deppman, A.; Arruda Neto, J.D.T.; Likhachev, V.P.; Goncalves, M.
2002-10-01
We use the recently developed MCMC/MCEF (Multi Collisional Monte Carlo plus Monte Carlo for Evaporation-Fission calculations) model to calculate the photo fissility and the photofission cross section at intermediate energies for the 243 Am and for 209 Bi, and compare them to results obtained for other actinides and to available experimental data. As expected, the results for 243 Am are close to those for 237 Np. The fissility for pre actinide nuclei is nearly one order of magnitude lower than that for the actinides. Both fissility and photofission cross section for 209 Bi are in good agreement with the experimental data. (author)
The Top-of-Instrument corrections for nuclei with AMS on the Space Station
Ferris, N. G.; Heil, M.
2018-05-01
The Alpha Magnetic Spectrometer (AMS) is a large acceptance, high precision magnetic spectrometer on the International Space Station (ISS). The top-of-instrument correction for nuclei flux measurements with AMS accounts for backgrounds due to the fragmentation of nuclei with higher charge. Upon entry in the detector, nuclei may interact with AMS materials and split into fragments of lower charge based on their cross-section. The redundancy of charge measurements along the particle trajectory with AMS allows for the determination of inelastic interactions and for the selection of high purity nuclei samples with small uncertainties. The top-of-instrument corrections for nuclei with 2 < Z ≤ 6 are presented.
Nuclei transmutation by collisions with fast hadrons and nuclei
International Nuclear Information System (INIS)
Strugalski, Z.; Strugalska-Gola, E.; Drzymala, A.
1998-01-01
Atomic nuclei change their mass- and charge-numbers if bombarded by fast hadrons and nuclei; the transmutation appears as a complicated process. It proceeds in a definite way - through a few stages or phases. Adequate identification of the nucleons and light nuclear fragments emitted and evaporated in a hadron-nucleus or nucleus-nucleus collisions and in the collision-induced intranuclear reactions allows one to estimate quantitatively the nuclei transmutations in the various stages (phases) of the process
International Nuclear Information System (INIS)
Gasparian, A.P.
1984-01-01
Results are presented from a bubble chamber experiment to search for anomalous mean free path (MFP) phenomena for secondary multicharged fragments (Zsub(f)=5 and 6) of the beam carbon nucleus at 4.2 GeV/c per nucleon. A total of 50000 primary interactions of carbon with propane (C 3 H 8 ) were created. Approximately 6000 beam tragments with charges Zsub(f)=5 and 6 were analyzed in detail to find out an anomalous decrease of MFP. The anomaly is observed only for secondary 12 C nuclei
International Nuclear Information System (INIS)
2001-01-01
The present collection of letters from JINR, Dubna, contains eight separate records on the interaction of high energy Λ 6 He hypernuclear beams with atomic nuclei, the position-sensitive detector of a high spatial resolution on the basis of a multiwire gas electron multiplier, pseudorapidity hadron density at the LHC energy, high precision laser control of the ATLAS tile-calorimeter module mass production at JINR, a new approach to ECG's features recognition involving neural network, subcriticity of a uranium target enriched in 235 U, beam space charge effects in high-current cyclotron injector CI-5, a homogeneous static gravitational field and the principle of equivalence
Beckmann, Volker
2012-01-01
This AGN textbook includes phenomena based on new results in the X-Ray domain from new telescopes such as Chandra and XMM Newton not mentioned in any other book. Furthermore, it considers also the Fermi Gamma Ray Space Telescope with its revolutionary advances of unprecedented sensitivity, field of view and all-sky monitoring. Those and other new developments as well as simulations of AGN merging events and formations, enabled through latest super-computing capabilities. The book gives an overview on the current knowledge of the Active Galacitc Nuclei phenomenon. The spectral energy d
Elementary excitations in nuclei
International Nuclear Information System (INIS)
Lemmer, R.H.
1987-01-01
The role of elementary quasi-particle and quasi-hole excitations is reviewed in connection with the analysis of data involving high-lying nuclear states. This article includes discussions on: (i) single quasi-hole excitations in pick-up reactions, (ii) the formation of single quasi-hole and quasi-particle excitations (in different nuclei) during transfer reactions, followed by (iii) quasi-particle quasi-hole excitations in the same nucleus that are produced by photon absorption. Finally, the question of photon absorption in the vicinity of the elementary Δ resonance is discussed, where nucleonic as well as nuclear degrees of freedom can be excited
International Nuclear Information System (INIS)
2000-01-01
The present collection of letters from JINR, Dubna, contains six separate records on the DELPHI experiment at LEP, the Fermi-surface dynamics of rotating nuclei, production of large samples of the silica dioxide aerogel in the 37-litre autoclave and test of its optical properties, preliminary radiation resource results on scintillating fibers, a new algorithm for the direct transformation method of time to digital with the high time resolution and development and design of analogue read-out electronics for HADES drift chamber system
International Nuclear Information System (INIS)
Baldin, A.M.; Bondarev, V.K.; Golovanov, L.B.
1977-01-01
Limit fragmentation of light nuclei (deuterium, helium) bombarded with 8,6 GeV/c protons was investigated. Fragments (pions, protons and deuterons) were detected within the emission angle 50-150 deg with regard to primary protons and within the pulse range 150-180 MeV/c. By the kinematics of collision of a primary proton with a target at rest the fragments observed correspond to a target mass upto 3 GeV. Thus, the data obtained correspond to teh cumulation upto the third order
Blandford, RD; Woltjer, L
1990-01-01
Starting with this volume, the Lecture Notes of the renowned Advanced Courses of the Swiss Society for Astrophysics and Astronomy will be published annually. In each course, three extensive lectures given by leading experts in their respective fields cover different and essential aspects of the subject. The 20th course, held at Les Diablerets in April 1990, dealt with current research on active galactic nuclei; it represents the most up-to-date views on the subject, presented with particular regard for clarity. The previous courses considered a wide variety of subjects, beginning with ""Theory
Exotic nuclei and radioactive beams
International Nuclear Information System (INIS)
Chomaz, P.
1996-01-01
The Nuclei called exotic are all the nuclei that it is necessary to recreate in laboratory to study them. Their life time is too short -in relation to earth age- for it remains enough on earth. The researchers are going to have at their s disposal at GANIL (Caen) with the S.P.I.R.A.L. project, exotic nuclei beams and will study new kinds of nuclear reactions to better understand the atom nucleus. (N.C.). 2 refs., 9 figs
Isolation of Nuclei and Nucleoli.
Pendle, Alison F; Shaw, Peter J
2017-01-01
Here we describe methods for producing nuclei from Arabidopsis suspension cultures or root tips of Arabidopsis, wheat, or pea. These methods could be adapted for other species and cell types. The resulting nuclei can be further purified for use in biochemical or proteomic studies, or can be used for microscopy. We also describe how the nuclei can be used to obtain a preparation of nucleoli.
Maris polarization in neutron-rich nuclei
Directory of Open Access Journals (Sweden)
Shubhchintak
2018-03-01
Full Text Available We present a theoretical study of the Maris polarization effect and its application in quasi-free reactions to assess information on the structure of exotic nuclei. In particular, we explore the dependence of the polarization effect on neutron excess and neutron-skin thickness. We discuss the uncertainties in the calculations of triple differential cross sections and of analyzing powers due the choices of various nucleon–nucleon interactions and optical potentials and the limitations of the method. Our study implies that polarization variables in (p, 2p reactions in inverse kinematics can be an effective probe of single-particle structure of nuclei in radioactive-beam facilities.
International Nuclear Information System (INIS)
Nosov, V.G.; Kamchatnov, A.M.
A consistent theory of the shell and magic oscillations of the masses of spherical nuclei is developed on the basis of the Fermi liquid concept of the energy spectrum of nuclear matter. A ''magic'' relationship between the system's dimensions and the limiting momentum of the quasi-particle distribution is derived; an integer number of the de Broglie half-waves falls on the nuclear diameter. An expression for the discontinuity in the nucleon binding energy in the vicinity of a magic nucleus is obtained. The role of the residual interaction is analyzed. It is shown that the width of the Fermi-surface diffuseness due to the residual interaction is proportional to the squared vector of the quasi-particle orbital angular momentum. The values of the corresponding proportionality factors (the coupling constant for quasi particles) are determined from the experimental data for 52 magic nuclei. The rapid drop of the residual interaction with increasing nuclear size is demonstrated. (7 figures, 3 tables) (U.S.)
Stability of superheavy nuclei
Pomorski, K.; Nerlo-Pomorska, B.; Bartel, J.; Schmitt, C.
2018-03-01
The potential-energy surfaces of an extended set of heavy and superheavy even-even nuclei with 92 ≤Z ≤126 and isospins 40 ≤N -Z ≤74 are evaluated within the recently developed Fourier shape parametrization. Ground-state and decay properties are studied for 324 different even-even isotopes in a four-dimensional deformation space, defined by nonaxiality, quadrupole, octupole, and hexadecapole degrees of freedom. Nuclear deformation energies are evaluated in the framework of the macroscopic-microscopic approach, with the Lublin-Strasbourg drop model and a Yukawa-folded mean-field potential. The evolution of the ground-state equilibrium shape (and possible isomeric, metastable states) is studied as a function of Z and N . α -decay Q values and half-lives, as well as fission-barrier heights, are deduced. In order to understand the transition from asymmetric to symmetric fission along the Fm isotopic chain, the properties of all identified fission paths are investigated. Good agreement is found with experimental data wherever available. New interesting features about the population of different fission modes for nuclei beyond Fm are predicted.
Cluster structures in light nuclei
International Nuclear Information System (INIS)
Horiuchi, H.
2000-01-01
Complete text of publication follows. Clustering in neutron-rich nuclei is discussed. To understand the novel features (1,2,3) of the clustering in neutron-rich nuclei, the basic features of the clustering in stable nuclei (4) are briefly reviewed. In neutron-rich nuclei, the requirement of the stability of clusters is questioned and the threshold rule is no more obeyed. Examples of clustering in Be and B isotopes (4,5) are discussed in some detail. Possible existence of novel type of clustering near neutron dripline is suggested (1). (author)
Level structures in Yb nuclei far from stable nuclei
International Nuclear Information System (INIS)
Hashizume, Akira
1982-01-01
Applying n-γ, γ-γ coincidence techniques, the excited levels in 158 Yb and in 157 Yb nuclei were studied. Stress is placed ona neutron detection technique to assign (HI,xn) reactions which produce the nuclei far from β stability line. (author)
Electron scattering off nuclei
International Nuclear Information System (INIS)
Gattone, A.O.
1989-01-01
Two recently developed aspects related to the scattering of electrons off nuclei are presented. On the one hand, a model is introduced which emphasizes the relativistic aspects of the problem in the impulse approximation, by demanding strict maintenance of the algebra of the Poincare group. On the other hand, the second model aims at a more sophisticated description of the nuclear response in the case of collective excitations. Basically, it utilizes the RPA formalism with a new development which enables a more careful treatment of the states in the continuum as is the case for the giant resonances. Applications of both models to the description of elastic scattering, inelastic scattering to discrete levels, giant resonances and the quasi-elastic region are discussed. (Author) [es
Antideuteron annihilation on nuclei
International Nuclear Information System (INIS)
Cugnon, J.
1992-01-01
An investigation of antideuteron annihilation on nuclei within an intranuclear cascade (INC) model is presented. Two models are set up to describe the annihilation itself, which either implies the antideuteron as a whole and occurs at a single point, or which may be considered as two independent nucleon-antinucleon annihilation occurring at different points and different times. Particular attention is paid to the energy transferred from the pions issued from the annihilation to the nuclear system and to the possibility of having a multifragmentation of the target. The latter feature is investigated within a percolation model. The pion distribution and the energy distribution are also discussed. Predictions of proton multiplicity distributions are compared with experiment. (orig.)
International Nuclear Information System (INIS)
2002-01-01
The present collection of letters from JINR, Dubna, contains ten separate records on Wien filter using in exploring on low-energy radioactive nuclei, memory effects in dissipative nucleus-nucleus collision, topological charge and topological susceptibility in connection with translation and gauge invariance, solutions of the multitime Dirac equation, the maximum entropy technique. System's statistical description, the charged conductor inside dielectric. Solution of boundary condition by means of auxiliary charges and the method of linear algebraic equations, optical constants of the TGS single crystal irradiated by power pulsed electron beam, interatomic pair potential and n-e amplitude from slow neutron scattering by noble gases, the two-coordinate multiwire proportional chamber of the high spatial resolution and neutron drip line in the region of O-Mg isotopes
International Nuclear Information System (INIS)
Xu, Renxin
2011-01-01
What is the real nature of pulsars? This is essentially a question of the fundamental strong interaction between quarks at low-energy scale and hence of the non-perturbative quantum chromo-dynamics, the solution of which would certainly be meaningful for us to understand one of the seven millennium prize problems (i.e., "Yang-Mills Theory") named by the Clay Mathematical Institute. After a historical note, it is argued here that a pulsar is very similar to an extremely big nucleus, but is a little bit different from the gigantic nucleus speculated 80 years ago by L. Landau. The paper demonstrates the similarity between pulsars and gigantic nuclei from both points of view: the different manifestations of compact stars and the general behavior of the strong interaction. (author)
Following the pioneering discovery of alpha clustering and of molecular resonances, the field of nuclear clustering is today one of those domains of heavy-ion nuclear physics that faces the greatest challenges, yet also contains the greatest opportunities. After many summer schools and workshops, in particular over the last decade, the community of nuclear molecular physicists has decided to collaborate in producing a comprehensive collection of lectures and tutorial reviews covering the field. This third volume follows the successful Lect. Notes Phys. 818 (Vol. 1) and 848 (Vol. 2), and comprises six extensive lectures covering the following topics: - Gamma Rays and Molecular Structure - Faddeev Equation Approach for Three Cluster Nuclear Reactions - Tomography of the Cluster Structure of Light Nuclei Via Relativistic Dissociation - Clustering Effects Within the Dinuclear Model : From Light to Hyper-heavy Molecules in Dynamical Mean-field Approach - Clusterization in Ternary Fission - Clusters in Light N...
International Nuclear Information System (INIS)
Afnan, I.R.; Thomas, A.W.
1976-01-01
A method has been suggested for relating μ-capture in nuclei to pion absorption through partially conserved axial vector current hypothesis. The success of the method relies heavily on the knowledge of the pion absorption amplitude at a momentum transfer equal to the μ-meson mass. That is we need to know the pion absorption amplitude off the mass-shell. The simplest nucleus for which this suggestion can be examined is μ-capture in deuterium. The Koltum-Reitan model is used to determine the pion absorption amplitude off the mass shell. In particular the senstivity of this off-mass-shell extrapolution to details of the N-N interaction is studied. (author)
Collective excitations in nuclei
International Nuclear Information System (INIS)
Chomaz, Ph.
1998-01-01
The properties of the nucleus cannot be reduced to the properties of its constituents: it is a complex system. The fact that many properties of the nucleus are consequences of the existence of mean-field potential is a manifestation of this complexity. In particular, the nucleons can thus self-organize in collective motions such as giant resonances. Therefore the study of this collective motions is a very good tool to understand the properties of the nucleus itself. The purpose of this article is to stress some aspects of these collective vibrations. We have studied how an ensemble of fermions as the nucleus can self-organize in collective vibrations which are behaving like a gas of bosons in weak interaction. Understanding of these phenomena remains one of the important subjects of actuality in the context of quantal systems in strong interaction. In particular, the study of the states with one or two vibration quanta provides a direct information on the structure of nuclei close to their ground states. Moreover, some collective states appear to be very robust against the onset of chaos. This is the case of the hot giant dipole built on top of a hot nucleus which seems to survive up to rather high temperatures. Their sudden disappearance is still a subject of controversy. It may be that the mean-field and the associated collective states are playing a crucial role also in catastrophic processes such as the phase-transitions. Indeed, when the system is diluted the collective vibrations may become unstable and it seems that these unstable modes provide a natural explanation to the self organization of the system in drops. Finally, considering the diversity of the different structures of exotic nuclei one may expect new vibration types. All these studies are showing the diversity of the collective motions of strongly correlated quantum systems such as the nucleus but many open questions remain to be solved. (authors)
International Nuclear Information System (INIS)
Casten, R.F.; Warner, D.D.
1982-01-01
The structure and characteristic properties and predictions of the IBA in deformed nuclei are reviewed, and compared with experiment, in particular for 168 Er. Overall, excellent agreement, with a minimum of free parameters (in effect, two, neglecting scale factors on energy differences), was obtained. A particularly surprising, and unavoidable, prediction is that of strong β → γ transitions, a feature characteristically absent in the geometrical model, but manifest empirically. Some discrepancies were also noted, principally for the K=4 excitation, and the detailed magnitudes of some specific B(E2) values. Considerable attention is paid to analyzing the structure of the IBA states and their relation to geometric models. The bandmixing formalism was studied to interpret both the aforementioned discrepancies and the origin of the β → γ transitions. The IBA states, extremely complex in the usual SU(5) basis, are transformed to the SU(3) basis, as is the interaction Hamiltonian. The IBA wave functions appear with much simplified structure in this way as does the structure of the associated B(E2) values. The nature of the symmetry breaking of SU(3) for actual deformed nuclei is seen to be predominantly ΔK=0 mixing. A modified, and more consistent, formalism for the IBA-1 is introduced which is simpler, has fewer free parameters (in effect, one, neglecting scale factors on energy differences), is in at least as good agreement with experiment as the earlier formalism, contains a special case of the 0(6) limit which corresponds to that known empirically, and appears to have a close relationship to the IBA-2. The new formalism facilitates the construction of contour plots of various observables (e.g., energy or B(E2) ratios) as functions of N and chi/sub Q/ which allow the parameter-free discussion of qualitative trajectories or systematics
Collective excitations in nuclei
Energy Technology Data Exchange (ETDEWEB)
Chomaz, Ph. [Grand Accelerateur National d`Ions Lourds (GANIL), 14 - Caen (France); Collaboration: La Direction des Sciences de la Matiere du CEA (FR); Le Fonds National de la Recherche Scientifique de Belgique (BE)
1998-12-31
The properties of the nucleus cannot be reduced to the properties of its constituents: it is a complex system. The fact that many properties of the nucleus are consequences of the existence of mean-field potential is a manifestation of this complexity. In particular, the nucleons can thus self-organize in collective motions such as giant resonances. Therefore the study of this collective motions is a very good tool to understand the properties of the nucleus itself. The purpose of this article is to stress some aspects of these collective vibrations. We have studied how an ensemble of fermions as the nucleus can self-organize in collective vibrations which are behaving like a gas of bosons in weak interaction. Understanding of these phenomena remains one of the important subjects of actuality in the context of quantal systems in strong interaction. In particular, the study of the states with one or two vibration quanta provides a direct information on the structure of nuclei close to their ground states. Moreover, some collective states appear to be very robust against the onset of chaos. This is the case of the hot giant dipole built on top of a hot nucleus which seems to survive up to rather high temperatures. Their sudden disappearance is still a subject of controversy. It may be that the mean-field and the associated collective states are playing a crucial role also in catastrophic processes such as the phase-transitions. Indeed, when the system is diluted the collective vibrations may become unstable and it seems that these unstable modes provide a natural explanation to the self organization of the system in drops. Finally, considering the diversity of the different structures of exotic nuclei one may expect new vibration types. All these studies are showing the diversity of the collective motions of strongly correlated quantum systems such as the nucleus but many open questions remain to be solved. (authors) 304 refs., 53 figs., 5 tabs.
Spectroscopy of heavy fissionable nuclei
Indian Academy of Sciences (India)
2015-08-05
Aug 5, 2015 ... Nuclei in the actinide chain and beyond are prone to fission owing to ... mass nuclei are typically more difficult, because the intensity is .... j15/2 neutron alignments in a region where shell stablization effects are crucial.
Problem of ''deformed'' superheavy nuclei
International Nuclear Information System (INIS)
Sobiczewski, A.; Patyk, Z.; Muntian, I.
2000-08-01
Problem of experimental confirmation of deformed shapes of superheavy nuclei situated in the neighbourhood of 270 Hs is discussed. Measurement of the energy E 2+ of the lowest 2+ state in even-even species of these nuclei is considered as a method for this confirmation. The energy is calculated in the cranking approximation for heavy and superheavy nuclei. The branching ratio p 2+ /p 0+ between α decay of a nucleus to this lowest 2+ state and to the ground state 0+ of its daughter is also calculated for these nuclei. The results indicate that a measurement of the energy E 2+ for some superheavy nuclei by electron or α spectroscopy is a promising method for the confirmation of their deformed shapes. (orig.)
Directory of Open Access Journals (Sweden)
Holt Roy J.
2016-01-01
Full Text Available Electron scattering at very high Bjorken x from hadrons provides an excellent test of models, has an important role in high energy physics, and from nuclei, provides a window into short range correlations. Light nuclei have a key role because of the relatively well-known nuclear structure. The development of a novel tritium target for Jefferson Lab has led to renewed interest in the mass three system. For example, deep inelastic scattering experiments in the light nuclei provide a powerful means to determine the neutron structure function. The isospin dependence of electron scattering from mass-3 nuclei provide information on short range correlations in nuclei. The program using the new tritium target will be presented along with a summary of other experiments aimed at revealing the large-x structure of the nucleon.
Fusion excitation functions involving transitional nuclei
Energy Technology Data Exchange (ETDEWEB)
Rehm, K.E.; Jiang, C.L.; Esbensen, H. [and others
1995-08-01
Measurements of fusion excitation functions involving transitional nuclei {sup 78}Kr and {sup 100}Mo showed a different behavior at low energies, if compared to measurements with {sup 86}Kr and {sup 92}Mo. This points to a possible influence of nuclear structure on the fusion process. One way to characterize the structure of vibrational nuclei is via their restoring force parameters C{sub 2} which can be calculated from the energy of the lowest 2{sup +} state and the corresponding B(E2) value. A survey of the even-even nuclei between A = 28-150 shows strong variations in C{sub 2} values spanning two orders of magnitude. The lowest values for C{sub 2} are observed for {sup 78}Kr, {sup 104}Ru and {sup 124}Xe followed by {sup 74,76}Ge, {sup 74,76}Se, {sup 100}Mo and {sup 110}Pd. In order to learn more about the influence of {open_quotes}softness{close_quotes} on the sub-barrier fusion enhancement, we measured cross sections for evaporation residue production for the systems {sup 78}Kr + {sup 104}Ru and {sup 78}Kr + {sup 76}Ge with the gas-filled magnet technique. For both systems, fusion excitation functions involving the closed neutron shell nucleus {sup 86}Kr were measured previously. The data are presently being analyzed.
Interaction of slow pions with atomic nuclei
International Nuclear Information System (INIS)
Troitskij, M.A.; Tsybul'nikov, A.V.; Chekunaev, N.I.
1984-01-01
Interactions of slow pions with atomic nuclei near to pion condensation are investigated. From comparison of experimental data with the theoretical calculation results on the basis of precise microscopic approach not bound with the random phase approximation (RPA) nuclear matter fundamental parameters near a critical point can be found. Optical potential of slow pions in nuclei, πN-scattering amplitudes and lengths, π-atom level isotopic shift, phenomenon of single-nucleon pion absorption by nucleus, phenomenon of nuclear critical opalescence are considered. The results of πN-scattering lengths calculation, sup(40-44)Ca, sup(24-29)Mg, sup(16-18)O π-atom level shift are presented. It is shown that the presence of π-condensate in nuclei can explain the observed suppression of p-wave potential terms. The phenomenon of single-nucleon pion absorption by nucleus is one of direct experiments which permits to reveal the π-condensate. The nuclear opalescence phenomenon is manifested in increase of pion photoproduction reaction cross section for account of nucleus proximity to π-condensation as compared with the calculated in the Fermi-gas model. The suggested method for calculating precondensate phenomena operates the better, the nearer is the system to the condensation threshold whereas the RPA method in this region is inapplicable
Fusion and reactions of exotic nuclei
Directory of Open Access Journals (Sweden)
Sánchez-Benítez A.M.
2011-10-01
Full Text Available Close to the drip lines, the scattering cross sections of halo nuclei show a different behaviour as compared to the tightly bound projectiles of the stability line. Several experiments carried out in the last decade have been dedicated to investigate the competition between transfer, breakup and fusion channels at energies around and below the Coulomb barrier. The rather complex scenario gives rise to conﬂicting conclusions concerning the effect of breakup and transfer on reaction dynamics and the sub-barrier fusion process. In this work we discuss recent experimental ﬁndings in fusion and reactions of 6He halo nucleus at energies around the Coulomb barrier.
JENDL gas-production cross section file
International Nuclear Information System (INIS)
Nakagawa, Tsuneo; Narita, Tsutomu
1992-05-01
The JENDL gas-production cross section file was compiled by taking cross-section data from JENDL-3 and by using the ENDF-5 format. The data were given to 23 nuclei or elements in light nuclei and structural materials. Graphs of the cross sections and brief description on their evaluation methods are given in this report. (author)
International Nuclear Information System (INIS)
Dote, Akinobu; Akaishi, Yoshinori; Yamazaki, Toshimitsu
2005-01-01
New nuclei 'K-bar-Mesic Nuclei' having the strangeness are described. At first it is shown that the strongly attractive nature of K-bar N interaction is reasoned inductively from consideration of the relation between Kaonic hydrogen atom and Λ (1405) which is an excited state of hyperon Λ. The K-bar N interactions are reviewed and summarized into three categories: 1. Phenomenological approach with density dependent K-bar N interaction (DD), relativistic mean field (RMF) approach, and hybrid of them (RMF+DD). 2. Boson exchange model. 3. Chiral SU(3) theory. The investigation of some light K-bar-nuclei by Akaishi and Yamazaki using phenomenological K-bar N interaction is explained in detail. Studies by antisymmetrized molecular dynamics (AMD) approach are also presented. From these theoretical researches, the following feature of K-bar-mesic nuclei are revealed: 1) Ground state is discrete and bound by 100 MeV or more. 2) Density is very high in side the K-bar-mesic nuclei. 3) Strange structures develop which are not seen in ordinary nuclei. Finally some recent experiments to explore K-bar-mesic nuclei are reviewed. (S. Funahashi)
Monopole transitions in hot nuclei
International Nuclear Information System (INIS)
Sujkowski, Z.
1994-01-01
Monopole transitions can be a signature of shape changing in a hot, pulsating nucleus (the low energy E0 mode) and/or a measure of the compressibility of finite nuclei (GMR, the breathing mode). Experimental information pertaining to GMR is reviewed. Recipes for deducing the incompressibility modules for infinite nuclear matter from data on GMR are discussed. Astrophysical implications are outlined. The first attempts at locating the GMR strength in moderately hot nuclei are described. Prospects for improving the experimental techniques to make an observation of this strength in selected nuclei unambiguous are discussed. (author). 46 refs, 8 figs
Monopole transitions in hot nuclei
Energy Technology Data Exchange (ETDEWEB)
Sujkowski, Z. [Soltan Inst. for Nuclear Studies, Otwock-Swierk (Poland)
1994-12-31
Monopole transitions can be a signature of shape changing in a hot, pulsating nucleus (the low energy E0 mode) and/or a measure of the compressibility of finite nuclei (GMR, the breathing mode). Experimental information pertaining to GMR is reviewed. Recipes for deducing the incompressibility modules for infinite nuclear matter from data on GMR are discussed. Astrophysical implications are outlined. The first attempts at locating the GMR strength in moderately hot nuclei are described. Prospects for improving the experimental techniques to make an observation of this strength in selected nuclei unambiguous are discussed. (author). 46 refs, 8 figs.
Electron scattering for exotic nuclei
International Nuclear Information System (INIS)
Suda, T.
2013-01-01
An electron scattering facility is under construction in RIKEN RI Beam Factory, Japan, which is dedicated to the structure studies of short-lived nuclei. This is the world's first and currently only facility of its type. The construction is nearly completed, and the first electron scattering experiment off short-lived nuclei will be carried out in the beginning of next year. The charge density distributions of short-lived nuclei will be precisely determined by elastic electron scattering for the first time. Physics pursued at this facility including future perspectives are explained
Cavitation inception from bubble nuclei
DEFF Research Database (Denmark)
Mørch, Knud Aage
2015-01-01
, and experimental investigations of bubbles and cavitation inception have been presented. These results suggest that cavitation nuclei in equilibrium are gaseous voids in the water, stabilized by a skin which allows diffusion balance between gas inside the void and gas in solution in the surrounding liquid....... The cavitation nuclei may be free gas bubbles in the bulk of water, or interfacial gaseous voids located on the surface of particles in the water, or on bounding walls. The tensile strength of these nuclei depends not only on the water quality but also on the pressure-time history of the water. A recent model...
International Nuclear Information System (INIS)
Ayala, A.L.
1996-01-01
In this talk we present our detailed study (theory and numbers) on the shadowing corrections to the gluon structure functions for nuclei. Starting from rather controversial information on the nucleon structure function which is originated by the recent HERA data, we develop the Glauber approach for the gluon density in a nucleus based on Mueller formula and estimate the value of the shadowing corrections in this case. Then we calculate the first corrections to the Glauber approach and show that these corrections are big. Based on this practical observation we suggest the new evolution equation which takes into account the shadowing corrections and solve it. We hope to convince you that the new evolution equation gives a good theoretical tool to treat the shadowing corrections for the gluons density in a nucleus and, therefore, it is able to provide the theoretically reliable initial conditions for the time evolution of the nucleus-nucleus cascade. The initial conditions should be fixed both theoretically and phenomenologically before to attack such complicated problems as the mixture of hard and soft processes in nucleus-nucleus interactions at high energy or the theoretically reliable approach to hadron or/and parton cascades for high energy nucleus-nucleus interaction. 35 refs., 24 figs., 1 tab
Jolie, J
2002-01-01
All the elementary particles that make up matter (as do quarks, electrons, neutrinos....) are fermions, the particles that convey the fundamental interactions (as do photons, gluons, W, Z...) are bosons. Composite particles are either bosons, or fermions according to the number of fermions they contain: if this number is even the particle is a boson, otherwise it is a fermion. According to this rule a proton is a fermion and the He sup 4 atom is a boson. Symmetry plays an important role in the standard model, a symmetry is a transformation that connect bosons with other bosons or fermions with other fermions. Supersymmetry associates a boson with a fermion or a fermion with a boson, in fact supersymmetry connects nuclei that are not generally considered as akin. Supersymmetry has just been observed in low energy levels of Gold sup 1 sup 9 sup 5 sup - sup 1 sup 9 sup 6 and Platinum sup 1 sup 9 sup 4 - sup 1 sup 9 sup 5 , it means that the description of these energy levels is simplified and can be made by a co...
International Nuclear Information System (INIS)
Jolie, J.
2002-01-01
All the elementary particles that make up matter (as do quarks, electrons, neutrinos....) are fermions, the particles that convey the fundamental interactions (as do photons, gluons, W, Z...) are bosons. Composite particles are either bosons, or fermions according to the number of fermions they contain: if this number is even the particle is a boson, otherwise it is a fermion. According to this rule a proton is a fermion and the He 4 atom is a boson. Symmetry plays an important role in the standard model, a symmetry is a transformation that connect bosons with other bosons or fermions with other fermions. Supersymmetry associates a boson with a fermion or a fermion with a boson, in fact supersymmetry connects nuclei that are not generally considered as akin. Supersymmetry has just been observed in low energy levels of Gold 195-196 and Platinum 194 - 195 , it means that the description of these energy levels is simplified and can be made by a common set of quantum numbers. (A.C.)
Photon interactions with nuclei
International Nuclear Information System (INIS)
Thornton, S.T.; Sealock, R.M.
1989-01-01
This document is a progress report for DOE Grant No. FG05-89ER40501, A000. The grant began March, 1989. Our primary research effort has been expended at the LEGS project at Brookhaven National Laboratory. This report will summarize our present research effort at LEGS as well as data analysis and publications from previous experiments performed at SLAC. In addition the principal investigators are heavily involved in the CLAS collaboration in Hall B at CEBAF. We have submitted several letters of intent and proposals and have made commitments to construct experimental equipment for CEBAF. We expect our primary experimental effort to continue at LEGS until CEBAF becomes operational. This report will be divided into separate sections describing our progress at LEGS, SLAC, and CEBAF. We will also discuss our significant efforts in the education and training of both undergraduate and graduate students. Photon detectors are described as well as experiments on delta deformation in nuclei of quasielastic scattering and excitation of the delta by 4 He(e,e')
International Nuclear Information System (INIS)
Robertson, R.G.H.
1980-01-01
A summary of parity violating effects in nuclei is given. Thanks to vigorous experimental and theoretical effort, it now appears that a reasonably well-defined value for the weak isovector π-nucleon coupling constant can be obtained. There is one major uncertainty in the analysis, namely the M2/E1 mixing ratio for the 2.79 MeV transition in 21 Ne. This quantity is virtually impossible to calculate reliably and must be measured. If it turns out to be much larger than 1, then a null result in 21 Ne is expected no matter what the weak interaction, so an experimental determination is urgently needed. The most promising approach is perhaps a measurement of the pair internal conversion coefficient. Of course, a direct measurement of a pure isovector case is highly desirable, and it is to be hoped that the four ΔT = 1 experiments will be pushed still further, and that improved calculations will be made for the 6 Li case. Nuclear parity violation seems to be rapidly approaching an interesting and useful synthesis
International Nuclear Information System (INIS)
Arima, A.
2003-01-01
(1) There are symmetries in nature, and the concept of symmetry has been used in art and architecture. The symmetry is evaluated high in the European culture. In China, the symmetry is broken in the paintings but it is valued in the architecture. In Japan, however, the symmetry has been broken everywhere. The serious and interesting question is why these differences happens? (2) In this lecture, I reviewed from the very beginning the importance of the rotational symmetry in quantum mechanics. I am sorry to be too fundamental for specialists of nuclear physics. But for people who do not use these theories, I think that you could understand the mathematical aspects of quantum mechanics and the relation between the angular momentum and the rotational symmetry. (3) To the specialists of nuclear physics, I talked about my idea as follows: dynamical treatment of collective motions in nuclei by IBM, especially the meaning of the degeneracy observed in the rotation bands top of γ vibration and β vibration, and the origin of pseudo-spin symmetry. Namely, if there is a symmetry, a degeneracy occurs. Conversely, if there is a degeneracy, there must be a symmetry. I discussed some details of the observed evidence and this correspondence is my strong belief in physics. (author)
Collective excitations in nuclei
International Nuclear Information System (INIS)
Chomaz, Ph.
1997-01-01
The properties of the nucleus cannot be reduced to the properties of its constituents: it is a complex system. The fact that many properties of the nucleus are consequences of the existence of mean-field potential is a manifestation of this complexity. In particular the nucleons can thus self-organize in collective motions such as giant resonances. Therefore the study of these collective motions is a very good to understand the properties of the nucleus itself. The purpose of this article was to stress some aspects of these collective vibrations. In particular we have studied how an ensemble of fermions as the nucleus can self-organize in collective vibrations which are behaving like a gas of bosons in weak interaction. The understanding of these phenomena remains one of the important subjects of actually in the context of quantal systems in strong interaction. In particular the study of the states with one or two vibration quanta provides a direct information on the structure if nuclei close to their ground states. (author)
Collective excitations in nuclei
Energy Technology Data Exchange (ETDEWEB)
Chomaz, Ph
1997-12-31
The properties of the nucleus cannot be reduced to the properties of its constituents: it is a complex system. The fact that many properties of the nucleus are consequences of the existence of mean-field potential is a manifestation of this complexity. In particular the nucleons can thus self-organize in collective motions such as giant resonances. Therefore the study of these collective motions is a very good to understand the properties of the nucleus itself. The purpose of this article was to stress some aspects of these collective vibrations. In particular we have studied how an ensemble of fermions as the nucleus can self-organize in collective vibrations which are behaving like a gas of bosons in weak interaction. The understanding of these phenomena remains one of the important subjects of actually in the context of quantal systems in strong interaction. In particular the study of the states with one or two vibration quanta provides a direct information on the structure if nuclei close to their ground states. (author) 270 refs.
RIPL starter file parameter validation for actinide nuclei
International Nuclear Information System (INIS)
Maslov, V.M.; Porodzinskij, Yu.V.
1999-01-01
Nuclear reaction theory calculations are of particular importance for actinide nuclei data evaluation. Measured data base for 238-U provides a unique possibility to compare calculated data with measured total, elastic, inelastic, fission, capture, (n,2n), (n,3n) and (n,4n) cross section data up to 40 MeV
Transport theory of deep-inelastic collisions between heavy nuclei
International Nuclear Information System (INIS)
Ayik, S.; Noerenberg, W.; Schuermann, B.
1975-01-01
In collisions between heavy nuclei, the major part of the total cross-section is due to deep-inelastic processes. These processes have been studied within a quantum-statistical approach leading to transport equations of the Fokker-Planck type (generalized diffusion equation). Transport coefficients have been studied within a model. (orig./WL) [de
Confinement forces in fast backward nucleon production off nuclei
International Nuclear Information System (INIS)
Kopeliovich, B.Z.; Niedermayer, F.
1982-01-01
Multiple colour exchange mechanism is proposed to describe fast backward nucleon production off nuclei at high energies. Cross section of hd → psub(B)X reaction is calculated in the colour flux tube model. This contribution is found to dominate in the hard part of momentum spectra
Spectroscopy of very heavy nuclei with a view to study super-heavy nuclei
International Nuclear Information System (INIS)
Khalfallah, F.
2007-08-01
Within the recent years, the spectroscopic study of single particle orbitals of very heavy elements (VHE) has become possible with the development of increasingly efficient experimental setups. This allows us, through nuclear deformation, to access with these deformed nuclei to orbitals situated around the Fermi level in the spherical superheavy elements (SHE) and learn more about the nuclear structure of these nuclei. The aim of this work is the spectroscopic studies of heavy and very heavy elements. Because of the experimental difficulties associated with the fusion reactions in the VHE region, a detailed optimization studies is essential. Simulation of energy loss and angular straggling of these nuclei due to the interaction in the target and to neutron's evaporation was carried out and allowed us to optimize the angular acceptance of the separators according to the target thickness. An extensive survey and exploration in the VHE region was also conducted on the basis of cross section's systematics in the literature and simulations carried out using the statistical code Hivap. In this framework, the possible extension of the range of validity of a set of Hivap parameters was investigated. This work has enabled us to prepare a list of experiments of interest for the production of very heavy nuclei. In this thesis, our work was concentrated on the spectroscopy of the nuclei No 256 et Rf 256 for which two experimental proposals were accepted. The octupole deformations predicted in the actinides region is studied in another part of this thesis, a part witch is dedicated to the gamma spectroscopy of Pa 223 . The data from a new experiment carried out using the Jurogam-Ritu-Great setup are analysed and compared to previous results. They confirm the octupole deformed shape in this nucleus. (author)
Dynamic polarization of radioactive nuclei
International Nuclear Information System (INIS)
Kiselev, Yu.F.; Lyuboshits, V.L.; )
2001-01-01
Radioactive nuclei, embedded into a frozen polarized proton target, atr proposed to polarize by means of some dynamic polarization methods. Angular distributions of γ-quanta emitted ny 22 Na(3 + ) in the cascade β-γ-radiation are calculated. It is shown that this distribution does not depend on the spin temperature sing at the Boltzmann distribution of populations among the Zeeman magnetic substates, whereas the tensor polarization of quadrupole nuclei, placed in the electric field of the crystal, causes the considerable sing dependence. The new method promises wide opportunities for the magnetic structure investigations as well as for the study of spin-spin interaction dynamics of rare nuclei in dielectrics. Physical-technical advantages and disadvantages of the given method are discussed for the polarization of heavy nuclei in the on-line implantation mode [ru
The delta in nuclei. Experiments
International Nuclear Information System (INIS)
Roy-Stephan, M.
1989-01-01
Experimental aspects of the Δ excitation will be presented. The Δ excitation in nuclei will be compared to the free Δ excitation. Various probes will be reviewed and their specific features will be underlined [fr
Electron scattering for exotic nuclei
Indian Academy of Sciences (India)
2014-11-04
Nov 4, 2014 ... Research Center for Electron-Photon Science, Tohoku University, 1-2-1 ... nuclei precisely determined by elastic scattering [1]. .... In order to fulfill these requirements, a window-frame shaped dipole magnet with a gap.
Collisions between complex atomic nuclei
International Nuclear Information System (INIS)
Vaagen, J. S.
1977-08-01
The use of heavy ion accelerators in the study of nuclear structure and states is reviewed. The reactions discussed are the quasielastic reactions in which small amounts of energy and few particles are exchanged between the colliding nuclei. The development of heavy ion accelerators is also discussed, as well as detection equipment. Exotic phenomena, principally the possible existence of superheavy nuclei, are also treated. (JIW)
Energy Technology Data Exchange (ETDEWEB)
Anon.
1987-07-15
PANIC is the triennal International Conference on Particles and Nuclei, and judging from the latest PANIC, held in Kyoto from 20-24 April there is no need for panic yet. Faced with two pictures – one of nuclei described in nucleon and meson terms, and another of nucleons containing quarks and gluons – physicists are intrigued to know what new insights from the quark level can tell us about nuclear physics, or vice versa.
International Nuclear Information System (INIS)
Anon.
1987-01-01
PANIC is the triennal International Conference on Particles and Nuclei, and judging from the latest PANIC, held in Kyoto from 20-24 April there is no need for panic yet. Faced with two pictures – one of nuclei described in nucleon and meson terms, and another of nucleons containing quarks and gluons – physicists are intrigued to know what new insights from the quark level can tell us about nuclear physics, or vice versa
Investigation of copper nuclei
International Nuclear Information System (INIS)
Delfini, M.G.
1983-01-01
An extensive study has been performed on copper isotopes in the mass region A=63-66. The results of a precise measurement are presented on the properties of levels of 64 Cu and 66 Cu. They were obtained by bombarding the 63 Cu and 65 Cu nuclei with neutrons. The gamma spectra collected after capture of thermal, 2-keV, 24-keV neutrons have been analysed and combined to give a rather extensive set of precise level energies and gamma transition strengths. From the angular distribution of the gamma rays it is possible to obtain information concerning the angular momentum J of several low-lying states. The level schemes derived from such measurements have been used as a test for calculations in the framework of the shell model. The spectral distributions of eigenstates in 64 Cu for different configuration spaces are presented and discussed. In this study the relative importance of configurations with n holes in the 1f7/2 shell with n up to 16, are investigated. It is found that the results strongly depend on the values of the single-particle energies. The results of the spectral-distribution method were utilized for shell-model calculations. From the information obtained from the spectral analysis it was decided to adopt a configuration space which includes up to one hole in the 1f7/2 shell and up to two particles in the 1g9/2 shell. Further, restrictions on seniority and on the coupling of the two particles in the 1g9/2 orbit have been applied and their effects have been studied. It is found that the calculated excitation energies reproduce the measured values in a satisfactory way, but that some of the electromagnetic properties are less well in agreement with experimental data. (Auth.)
Energy Technology Data Exchange (ETDEWEB)
Heenen, P.H. [Universite Libre de Bruxelles, Service de Physique Nucleaire Theorique (Belgium); Nazarewicz, W. [Tennessee Univ., Knoxville, TN (United States). Dept. of Physics; Warsaw Univ. (Poland). Inst. Fizyki Teoretycznej
2002-02-01
This article draws the long history of the discovery of new heavy nuclei since its beginning in 1940 when neptunium was found, and presents the current status of research in this field. The last 3 years have brought a number of experimental surprises which have truly rejuvenated the field. In January 1999, scientists from Dubna (Russia) reported the synthesis of 1 atom of element 114 ({sup 298}Uuq) in a hot fusion reaction between a {sup 48}Ca beam and a {sup 244}Pu target. This discovery was followed by 3 other reports from Dubna. First using the {sup 242}Pu({sup 48}Ca,3n) reaction, they produced {sup 287}Uuq. In 1999 the synthesis of another isotope of Z=114, the even-even {sup 288}Uuq was reported. The element Z=116 ({sup 292}Uuh) was discovered as a product of the {sup 248}Cm({sup 48}Ca,4n) reaction. The GSI (Germany) group found a new even isotope of the element 110: {sup 270}Uun and also {sup 272}Uuu (element 111) and {sup 277}Uub (element 112). 2 new isotopes of the element 107: {sup 266}Bh and {sup 267}Bh have been found at Berkeley (Usa). The synthesis of the new element Z=118 ({sup 293}Uuo) announced in 1999 by the Berkeley group was retracted 2 years later. The lifetimes reported for the elements {sup 284}Uub and {sup 280}Uun are by many orders of magnitude longer than those of the isotopes with Z{<=}112 previously discovered at GSI. (A.C.)
The morphology of cometary nuclei
Keller, H. U.; Jorda, L.
comets display residual activity or clouds of dust grains around their nuclei. Taking the residual signal into account (mostly using simple models for the brightness distribution) the size estimates of the nuclei could be improved. The (nuclear) magnitude of a comet depends on the product of its albedo and cross-section. Only in a few cases could the albedo and size of a cometary nucleus be separated by additional observation of its thermal emission at infrared wavelengths. By comparison with outer Solar System asteroids Cruikshank et al. (1985) derived a surprisingly low albedo of about 0.04. A value in clear contradiction to the perception of an icy surface but fully confirmed by the first resolved images of a cometary nucleus during the flybys of the Vega and Giotto spacecraft of comet Halley (Sagdeev et al. 1986, Keller et al. 1986). The improvements of radar techniques led to the detection of reflected signals and finally to the derivation of nuclear dimensions and rotation rates. The observations, however, are also model dependent (rotation and size are similarly interwoven as are albedo and size) and sensitive to large dust grains in the vicinity of a nucleus. As an example, Kamoun et al. (1982) determined the radius of comet Encke to 1.5 (2.3, 1.0) km using the spin axis determination of Whipple and Sekanina (1979). The superb spatial resolution of the Hubble Space Telescope (HST) is not quite sufficient to resolve a cometary nucleus. The intensity distribution of the inner coma, however, can be observed and extrapolated toward the nucleus based on models of the dust distribution. If this contribution is subtracted from the central brightness the signal of the nucleus can be derived and hence its product of albedo times cross-section (Lamy and Toth 1995, Rembor 1998, Keller and Rembor 1998; Section 4.3). It has become clear that cometary nuclei are dark, small, often irregular bodies with dimensions ranging from about a kilometre (comet Wirtanen, the target of
Neutron induced reaction of light nuclei and its role in nuclear astrophysics
International Nuclear Information System (INIS)
Nagai, Y.
2000-01-01
Recently, much interest has arisen in the abundance of the s-process isotopes in stars of various metallicity to construct models of the chemical evolution of the Galaxy. Efforts involving both observations and yield estimations of these isotopes are being made for a wide range of metallicities and stellar masses to compare the chemical evolution models with the observational data. So far, in the models of the chemical evolution of the s-isotopes the yields of the isotopes versus the abundance of either 56 Fe (seed) nuclei or 16 O (source) nuclei have been suggested to be linear. However, it has now been shown to be nonlinear for low-metallicity massive stars. The nonlinearity was due to neutron poison by abundant light nuclei. Namely, if the neutron capture cross sections of the light nuclei would be large, the yields of heavier s-isotopes would decrease; the relationship of the yields versus the abundance of either 56 Fe (seed) or 16 O (source) nuclei becomes nonlinear; furthermore, the yields of p-process nuclei would decrease, since the s-process nuclei are the immediate predecessors of the p-nuclei. Therefore, in order to construct models to predict the s- and p-isotope productions as functions of the metallicity and stellar mass, it is necessary to know the neutron capture cross sections of light nuclei at stellar neutron energy. In the lecture, I discuss detailed motive of the study, together with results recently obtained. (author)
Measurement and analysis of large momenta in nuclei
International Nuclear Information System (INIS)
Force, P.
1986-06-01
Backward energetic proton cross sections are measured from 200 MeV proton beam on various targets. Data are analysed using the Quasi Two Body Scaling frame (single scattering on a nucleon). A scaling rule is found for large momenta. A (p-γ) coincidence experiment is performed to identify the residual nuclei and the excitation energy in the nuclei is measured. These results are in good agreement with the ''Q.T.B.S.'' Theory. A similar experiment with an electron beam shows the same momentum spectrum. An approach of short range correlation between nucleons is proposed. 35 refs [fr
Two-proton knockout on neutron-rich nuclei
International Nuclear Information System (INIS)
Bazin, D.; Brown, B.A.; Campbell, C.M.; Church, J.A.; Dinca, D.C.; Enders, J.; Gade, A.; Glasmacher, T.; Hansen, P.G.; Mueller, W.F.; Olliver, H.; Perry, B.C.; Sherrill, B.M.; Terry, J.R.; Tostevin, J.A.
2004-01-01
Two-proton knockout reactions on neutron-rich nuclei [Phys. Rev. Lett. 91 (2003) 012501] have been studied in inverse kinematics at intermediate energy. Strong evidence that the two-proton removal from a neutron-rich system proceeds as a direct reaction is presented, together with a preliminary theoretical discussion of the partial cross sections based on eikonal reaction theory and the many-body shell model. They show that this reaction can be used to characterize the wave functions of the projectiles and holds great promise for the study of neutron-rich nuclei
International Nuclear Information System (INIS)
Pivovarov, Yu.L.; Shirokov, A.A.; Vorobiev, S.A.
1990-01-01
The energy dependence of electromagnetic excitation and electromagnetic disintegration cross sections for relativistic nuclei passing through crystals is investigated both theoretically and by means of computer simulation. For electromagnetic excitation, resonant peaks are found at definite energy values. An increase of electromagnetic excitation and disintegration cross sections in crystals at very high energies is found to be due to coherent addition of amplitudes. Numerical results are presented for the electric dipole excitation of fluorine nuclei and electromagnetic deuteron disintegration. (orig.)
From heavy nuclei to super-heavy nuclei
International Nuclear Information System (INIS)
Theisen, Ch.
2003-01-01
The existence of super-heavy nuclei has been predicted nearly fifty years ago. Due to the strong coulomb repulsion, the stabilisation of these nuclei is possible only through shell effects. The reasons for this fragile stability, as well as the theoretical predictions concerning the position of the island of stability are presented in the first part of this lecture. In the second part, experiments and experimental techniques which have been used to synthesize or search for super-heavy elements are described. Spectroscopic studies performed in very heavy elements are presented in the following section. We close this lecture with techniques that are currently being developed in order to reach the superheavy island and to study the structure of very-heavy nuclei. (author)
Complete destruction of heavy nuclei by hadrons and nuclei
International Nuclear Information System (INIS)
Tolstov, K.D.
1980-01-01
The total disintegration is considered of Ag and Pb nuclei and 4 He, 12 C nuclei With a momentum of 4.5 GeV/c per nucleon. It is shown that nucleons are mainly emitted, and there is no residual nUcleus the mass of which is comparable to that of the primary nucleus. The probability of total nucleus disintegration is considered as a function of projectile energy and the mass. The multiplicity, energy and emission angle of particles are considerred as well. It is shown that the density of nuclear matter in the overlap zone of colliding nuclei exceeds the usual one by a factor of approximately 4. A comparison is made with interaction models. A conclusion is drawn of the collective interaction mechanism (perhaps, of the shock wave type) of particle ejection from the target nucleus at the first stage of interaction and of explosive decay of the residual nucleus at the next one
Second proton and neutron alignments in the doubly-odd nuclei 154,156Tb
International Nuclear Information System (INIS)
Hartley, D.J.; Allen, J.L.; Brown, T.B.; Kondev, F.G.; Pfohl, J.; Riley, M.A.; Fischer, S.M.; Janssens, R.V.; Nisius, D.T.; Fallon, P.; Ma, W.C.; Simpson, J.
1999-01-01
High-spin states in the doubly-odd nuclei 154,156 Tb have been populated in two separate experiments using the 36 S+ 124 Sn reaction at different beam energies (160 and 175 MeV). The yrast structures of both nuclei were extended to much higher spin (I≤48ℎ) than previously known and several quasiparticle alignments have been identified. These include the second neutron alignment and a clear delineation of the second proton crossing in 156 Tb. Systematics of these crossings for odd-Z nuclei and comparisons with results of cranked shell model calculations are discussed. thinsp copyright 1999 The American Physical Society
International Nuclear Information System (INIS)
2002-01-01
The present collection of letters from JINR, Dubna, contains eight separate records on the role of the complanar emission of particles in nuclear interaction for E 0 >10 16 eV detected in the stratosphere, 10 B nucleus fragment yields, nuclear teleportation (proposal for an experiment), invisible 'glue' bosons in model field theory, calculation of the ionization differential effective cross sections in fast ion-atom collisions, interactions of ultracold neutrons near surface of solids, g factors as a probe for high-spin structure of neutron-rich Dy isotopes, search for periodicities in experimental data by the autoregressive model methods
Fusion probability and survivability in estimates of heaviest nuclei production
International Nuclear Information System (INIS)
Sagaidak, Roman
2012-01-01
A number of theoretical models have been recently developed to predict production cross sections for the heaviest nuclei in fusion-evaporation reactions. All the models reproduce cross sections obtained in experiments quite well. At the same time they give fusion probability values P fus ≡ P CN differed within several orders of the value. This difference implies a corresponding distinction in the calculated values of survivability. The production of the heaviest nuclei (from Cm to the region of superheavy elements (SHE) close to Z = 114 and N = 184) in fusion-evaporation reactions induced by heavy ions has been considered in a systematic way within the framework of the barrier-passing (fusion) model coupled with the standard statistical model (SSM) of the compound nucleus (CN) decay. Both models are incorporated into the HIVAP code. Available data on the excitation functions for fission and evaporation residues (ER) produced in very asymmetric combinations can be described rather well within the framework of HIVAP. Cross-section data obtained in these reactions allow one to choose model parameters quite definitely. Thus one can scale and fix macroscopic (liquid-drop) fission barriers for nuclei involved in the evaporation-fission cascade. In less asymmetric combinations (with 22 Ne and heavier projectiles) effects of fusion suppression caused by quasi-fission are starting to appear in the entrance channel of reactions. The P fus values derived from the capture-fission and fusion-fission cross-sections obtained at energies above the Bass barrier were plotted as a function of the Coulomb parameter. For more symmetric combinations one can deduce the P fus values semi-empirically, using the ER and fission excitation functions measured in experiments, and applying SSM model with parameters obtained in the analysis of a very asymmetric combination leading to the production of (nearly) the same CN, as was done for reactions leading to the pre-actinide nuclei formation
Reflection asymmetric shapes in nuclei
International Nuclear Information System (INIS)
Ahmad, I.; Carpenter, M.P.; Emling, H.
1989-01-01
Experimental data show that there is no even-even nucleus with a reflection asymmetric shape in its ground state. Maximum octupole- octupole correlations occur in nuclei in the mass 224 (N∼134, Z∼88) region. Parity doublets, which are the characteristic signature of octupole deformation, have been observed in several odd mass Ra, Ac and Pa nuclei. Intertwined negative and positive parity levels have been observed in several even-even Ra and Th nuclei above spin ∼8ℎ. In both cases, the opposite parity states are connected by fast El transitions. In some medium-mass nuclei intertwined negative and positive parity levels have also been observed above spin ∼7ℎ. The nuclei which exhibit octupole deformation in this mass region are 144 Ba, 146 Ba and 146 Ce; 142 Ba, 148 Ce, 150 Ce and 142 Xe do not show these characteristics. No case of parity doublet has been observed in the mass 144 region. 32 refs., 16 figs., 1 tab
Decay properties of nuclei in the neighbourhood of 100Sn
International Nuclear Information System (INIS)
Straub, Katrin
2011-01-01
This thesis concentrates on nuclear properties of very neutron deficient nuclei near the proton dripline in the neighbourhood of doubly-magic 100 Sn. In an experiment performed in March 2008 at the GSI in Darmstadt, the exotic nuclei were produced in a projectile fragmentation reaction using a 124 Xe primary beam with an energy of 100 AMeV impinging on a 4000 Beryllium target, separated and identified in the FRS and eventually stopped for decay spectroscopy in a complex implantation detector developed at the institute E12. The Germanium array RISING was employed for the measurement of prompt and delayed gamma radiation. Production cross sections and half lives were determined along the proton dripline. The isotopes 99 Sn, 97 In and 95 Cd were identified for the first time. additional nuclei studied in this thesis are 103 Sn, 96 Cd as well as the two tin isotopes 101 Sn and 102 Sn. (orig.)
Shell model Monte Carlo investigation of rare earth nuclei
International Nuclear Information System (INIS)
White, J. A.; Koonin, S. E.; Dean, D. J.
2000-01-01
We utilize the shell model Monte Carlo method to study the structure of rare earth nuclei. This work demonstrates the first systematic full oscillator shell with intruder calculations in such heavy nuclei. Exact solutions of a pairing plus quadrupole Hamiltonian are compared with the static path approximation in several dysprosium isotopes from A=152 to 162, including the odd mass A=153. Some comparisons are also made with Hartree-Fock-Bogoliubov results from Baranger and Kumar. Basic properties of these nuclei at various temperatures and spin are explored. These include energy, deformation, moments of inertia, pairing channel strengths, band crossing, and evolution of shell model occupation numbers. Exact level densities are also calculated and, in the case of 162 Dy, compared with experimental data. (c) 2000 The American Physical Society
Source spectral index of heavy cosmic ray nuclei
International Nuclear Information System (INIS)
Engelmann, J.J.; Ferrando, P.; Koch-Miramond, L.; Masse, P.; Soutoul, A.; Webber, W.R.
1985-08-01
From the energy spectra of the heavy nuclei observed by the French-Danish experiment on HEAO-3, we have derived the source spectra of the mostly primary nuclei (C, O, Ne, Mg, Si, Ca and Fe) in the framework of an energy dependent leaky box model (Engelmann et al. 1985). In the present paper we want to derive more accurate spectral indices by using better values of the escape length based on the latest cross section measurements (Webber 1984, Soutoul et al. this conference). Our aim is also to extend the analysis to lower energies down to 0.4 GeV/n (kinetic energy observed near earth), using data obtained by other groups. The only nuclei for which we have a good data base in a broad range of energies are O and Fe, so the present study is restricted to these two elements
Possibilities at LAMPF for studying nuclei of astrophysical interest
International Nuclear Information System (INIS)
Talbert, W.L. Jr.; Bunker, M.E.
1985-01-01
Nuclear data needs in astrophysics range from neutron capture cross sections of a number of stable or near-stable nuclei to decay and neutron binding-energy data for highly neutron-rich nuclei. LAMPF has the potential to contribute significantly to these needs. The new Los Alamos Neutron Scattering Center (LANSCE, aka WNR/PSR) offers world-class capabilities for neutron capture studies up to an MeV or so. The study of nuclei far from stability could be extended into some regions of astrophysical interest using a proposed He-jet coupled mass separator system with a target/production chamber in the LAMPF beam stop area. Specific examples of possible studies at each facility are presented
Energy Technology Data Exchange (ETDEWEB)
Grosjean, C
2005-03-15
The thorium-U{sup 233} fuel cycle might provided safer and cleaner nuclear energy than the present Uranium/Pu fuelled reactors. Over the last 10 years, a vast campaign of measurements has been initiated to bring the precision of neutron data for the key nuclei (Th{sup 232}, Pa{sup 233} and U{sup 233}) at the level of those for the U-Pu cycle. This is the framework of these measurements, the energy dependent neutron induced fission cross section of Th{sup 232} and U{sup 233} has been measured from 1 to 7 MeV with a target accuracy lesser than 5 per cent. These measurements imply the accurate determination of the fission rate, the number of the target nuclei as well as the incident neutron flux impinging on the target, the latter has been obtained using the elastic scattering (n,p). The cross section of which is very well known in a large neutron energy domain ({approx} 0,5 % from 1 eV to 50 MeV) compared to the U{sup 235}(n,f) reaction. This technique has been applied for the first time to the Th{sup 232}(n,f) and U{sup 233}(n,f) cases. A Hauser-Feshbach statistical model has been developed. It consists of describing the different decay channels of the compound nucleus U{sup 234} from 0,01 to 10 MeV neutron energy. The parameters of this model were adjusted in order to reproduce the measured fission cross section of U{sup 233}. From these parameters, the cross sections from the following reactions could be extracted: inelastic scattering U{sup 233}(n,n'), radiative capture U{sup 233}(n,{gamma}) and U{sup 233}(n,2n). These cross sections are still difficult to measure by direct neutron reactions. The calculated values have allowed us to fill the lack of experimental data for the major fissile nucleus of the thorium cycle. (author)
A study of the giant dipole resonance in doubly even tellurium and cerium isotopes
International Nuclear Information System (INIS)
Lepretre, A.; Beil, H.; Bergere, R.; Carlos, P.; Fagot, J.; Miniac, A. de; Veyssiere, A.
1976-01-01
The partial photoneutron cross sections [sigma(γ,n)+sigma(γ,pn)] and sigma(γ,2n) of 124 Te, 126 Te, 128 Te, 130 Te and 140 Ce, 142 Ce were measured in the giant dipole resonance region by means of the monochromatic photon beam installation at SACLAY. Absolute total photoneutron cross sections, Lorentz line parameters and integrated cross sections are evaluated. The experimental behaviour of the GDR for the above nuclei and in particular its spreading, is then tentatively interpreted in terms of the improved dynamic collective model using the concept of potential energy surfaces. (Auth.)
Protonic decay of oriented nuclei
International Nuclear Information System (INIS)
Kadmensky, S.G.
2002-01-01
On the basis of the multiparticle theory of protonic decay, the angular distributions of protons emitted by oriented spherical and deformed nuclei in the laboratory frame and in the internal coordinate frame of deformed parent nuclei are constructed with allowance for symmetry with respect to time inversion. It is shown that, because of the deep-subbarrier character of protonic decay, the adiabatic approximation is not applicable to describing the angular distributions of protons emitted by oriented deformed nuclei and that the angular distribution of protons in the laboratory frame does not coincide with that in the internal coordinate frame. It is demonstrated that these angular distributions coincide only if the adiabatic and the semiclassical approximation are simultaneously valid
International Nuclear Information System (INIS)
Oyamatsu, K.; Yamada, M.
1994-01-01
We report on the recent progress in understanding the matter in the crust of a neutron star. For nuclides in the outer crust, recently measured masses of neutron-rich nuclei enable us to determine more accurately the stable nuclide as a function of the matter density. In the inner crust, the compressible liquid-drop model predicts successive change of the nuclear shape, from sphere to cylinder, slab, cylindrical hole and spherical hole at densities just before the transition to uniform matter. In order to go beyond the liquiddrop model, we performed the Thomas-Fermi calculation paying special attention to the surface diffuseness, and have recently calculated the shell energies of the non-spherical nuclei. We have found from these studies that all these non-spherical nuclei exist stably in the above order even if we include the surface diffuseness and shell energies. (author)
Nuclei, hadrons, and elementary particles
International Nuclear Information System (INIS)
Bopp, F.W.
1989-01-01
This book is a short introduction to the physics of the nuclei, hadrons, and elementary particles for students of physics. Important facts and model imaginations on the structure, the decay, and the scattering of nuclei, the 'zoology' of the hadrons and basic facts of hadronic scattering processes, a short introduction to quantum electrodynamics and quantum chromodynamics and the most important processes of lepton and parton physics, as well as the current-current approach of weak interactions and the Glashow-Weinberg-Salam theory are presented. (orig.) With 153 figs., 10 tabs [de
Octupole shapes in heavy nuclei
International Nuclear Information System (INIS)
Ahmad, I.
1994-01-01
Theoretical calculations and measurements show the presence of strong octupole correlations in thecyround states and low-lying states of odd-mass and odd-odd nuclei in the RaPa region. Evidence for octupole correlations is provided by the observation of parity doublets and reductions in M1 matrix elements, decoupling parameters, and Coriolis matrix elements Involving high-j states. Enhancement of E1 transition rates has also been observed for some of the octupole deformed nuclei. The most convincing argument for octupole deformation is provided by the similarities of the reduced alpha decay rates to the two members of parity doublets
International Nuclear Information System (INIS)
Nomura, T.
1991-12-01
The Exotic Nuclei Arena planned in Japanese Hadron Project aims to accelerate various unstable nuclei produced in 1-GeV proton-induced reactions up to 6.5 MeV/u by means of heavy-ion linacs. The present status of research and development for the Earena is briefly reported. The construction of the prototype facility to accelerate unstable beams up to 0.8 MeV/u is planned in 1992-94, in which the existing cyclotron in INS is used as the primary accelerator. (author)
Spinodal decomposition of atomic nuclei
Energy Technology Data Exchange (ETDEWEB)
Chomaz, P. [Grand Accelerateur National d`Ions Lourds (GANIL), 14 - Caen (France); Colonna, M.; Guarnera, A. [Grand Accelerateur National d`Ions Lourds (GANIL), 14 - Caen (France)]|[LNS, Catania (Italy)
1996-12-31
Multifragmentation of atomic nuclei is discussed. It is shown that this description of the dynamics of first order phase transitions in infinite and finite system is now partially achieved. An important conclusion is that in some specific cases well-defined collective motions were initiating the self-organisation of the unstable matter in fragments. In the case of finite systems the possible signals kept from this early fragmentation stage can inform on the possible occurrence of a liquid-gas phase transition in nuclei. (K.A.). 21 refs.
Spinodal decomposition of atomic nuclei
International Nuclear Information System (INIS)
Chomaz, P.; Colonna, M.; Guarnera, A.
1996-01-01
Multifragmentation of atomic nuclei is discussed. It is shown that this description of the dynamics of first order phase transitions in infinite and finite system is now partially achieved. An important conclusion is that in some specific cases well-defined collective motions were initiating the self-organisation of the unstable matter in fragments. In the case of finite systems the possible signals kept from this early fragmentation stage can inform on the possible occurrence of a liquid-gas phase transition in nuclei. (K.A.)
Are there superheavy atomic nuclei
International Nuclear Information System (INIS)
Herrmann, G.
1982-04-01
The author presents a populary introduction to the formation of nuclei with special regards to superheavy nuclei. After a general description of the methods of physics the atomic hypothesis is considered. Thereafter the structure of the nucleus is discussed, and the different isotopes are considered. Then radioactivity is described as an element transmutation. Thereafter the thermonuclear reactions in the sun are considered. Then the synthesis of elements using heavy ion reactions is described. In this connection the transuranium elements and the superheavy elements are considered. (orig./HSI) [de
STELLAR TRANSITS IN ACTIVE GALACTIC NUCLEI
International Nuclear Information System (INIS)
Béky, Bence; Kocsis, Bence
2013-01-01
Supermassive black holes (SMBHs) are typically surrounded by a dense stellar population in galactic nuclei. Stars crossing the line of site in active galactic nuclei (AGNs) produce a characteristic transit light curve, just like extrasolar planets do when they transit their host star. We examine the possibility of finding such AGN transits in deep optical, UV, and X-ray surveys. We calculate transit light curves using the Novikov-Thorne thin accretion disk model, including general relativistic effects. Based on the expected properties of stellar cusps, we find that around 10 6 solar mass SMBHs, transits of red giants are most common for stars on close orbits with transit durations of a few weeks and orbital periods of a few years. We find that detecting AGN transits requires repeated observations of thousands of low-mass AGNs to 1% photometric accuracy in optical, or ∼10% in UV bands or soft X-ray. It may be possible to identify stellar transits in the Pan-STARRS and LSST optical and the eROSITA X-ray surveys. Such observations could be used to constrain black hole mass, spin, inclination, and accretion rate. Transit rates and durations could give valuable information on the circumnuclear stellar clusters as well. Transit light curves could be used to image accretion disks with unprecedented resolution, allowing us to resolve the SMBH silhouette in distant AGNs.
The mechanism of total disintegration of heavy nuclei by fast hadrons and nuclei
International Nuclear Information System (INIS)
Strugalska-Gola, E.; Strugalski, Z.
1997-01-01
The mechanism of the total disintegration of atomic nuclei by fast hadrons and nuclei is considered. The passage of energetic hadrons through layers of intranuclear matter, accompanied by emission of fast nucleons with kinetic energies from about 20 up to about 500 MeV from definite local small regions in the nuclei around projectile courses in them, allows one to explain simply the occurrence of the total destruction of nuclei involved in the collisions. Light nuclei may be totally disintegrated by fast hadrons and nuclei; heavier nuclei may be totally disintegrated only in central collisions of nuclei with similar mass numbers
Electrodisintegration of relativistic nuclei by a periodic crystal field in channeling
International Nuclear Information System (INIS)
Pivovarov, Yu.L.; Vorob'ev, S.A.
1981-01-01
Processes on channeled relativistic nuclei with transition into a continuous spectrum (electrodisintegration of nuclei with emission of neutron, proton, photon and etc.) are considered. A case of plane channeling is considered. The equivalent photon method is used for calculating the disintegration cross section. The beryllium disintegration cross section in the system of tungsten crystal (100) planes is calculated. At the γ=10 2 Lorentz factor the cross section value is 5.27 mb. The process considered is of interest from the viewpoint of production of monoenergy neutrons of high energies and γ quanta of excited nuclei. The channeling effect gives the possibility to study electromagnetic interactions of relativistic nuclei under suppre--ssion conditions of the nuclear interaction channel [ru
Fission-evaporation competition in excited uranium and fermium nuclei
International Nuclear Information System (INIS)
Sagajdak, R.N.; Chepigin, V.I.; Kabachenko, A.P.
1997-01-01
The production cross sections and excitation functions for the 223-226 U neutron deficient isotopes have been measured in the 20 Ne+ 208 Pb and 22 Ne+ 208 Pb reactions for (4,5)n and (4-7)n evaporation channels of the de-excitation of the compound nuclei 228 U* and 230 U*, respectively. The present study considers in addition the de-excitation via the (5,6)n evaporation channels of the 224 U* compound nucleus formed in the 27 Al+ 197 Au reaction. The production cross sections of 247g,246 Fm formed after evaporation of (5,6)n and (7,8)n from the 252 Fm* and 254 Fm* compound nuclei produced in the 20 Ne+ 232 Th and 22 Ne+ 232 Th reactions were also measured respectively. The evaporation residues emerging from the target were separated in-flight from the projectiles and background reaction products by the electrostatic recoil separator VASSILISSA [1]. The investigation regards the U and Fm compound nuclei in the 40-80 MeV excitation energy range. For the analysis of the (Hl, xn) evaporation cross sections the advanced statistical model [2] calculations were used. The angular momentum dependence of the shell correction to the fission barrier, and the effects of the nuclear viscosity and dynamical deformation for these fissile excited nuclei are considered. The n /Γ t > values at the initial steps of the de-excitation cascade for the U and Fm compound nuclei were derived from the measured excitation functions and discussed from the point of view of the consequences for the fission process dynamics
Energy Technology Data Exchange (ETDEWEB)
Benites R, J. [Centro Estatal de Cancerologia de Nayarit, Servicio de Seguridad Radiologica, Calz. de la Cruz 118 Sur, 63000 Tepic, Nayarit (Mexico); Vega C, H. R. [Universidad Autonoma de Zacatecas, Unidad Academica de Estudios Nucleares, Apdo. Postal 336, 98000 Zacatecas (Mexico); Velazquez F, J., E-mail: jlbenitesr@prodigy.net.mx [Universidad Autonoma de Nayarit, Posgrado en Ciencias Biologico Agropecuarias, Carretera Tepic-Compostela Km 9, 63780 Jalisco-Nayarit (Mexico)
2012-10-15
Using Monte Carlo methods was modeled a solid water mannequin; according to the ICRU 44 (1989), Tissue substitutes in radiation dosimetry and measurements, of the International Commission on Radiation Units and Measurements; Report 44. This material Wt 1 is made of H (8.1%), C (67.2%), N (2.4%), O (19.9%), Cl (0.1%), Ca (2.3%) and its density is of 1.02 gr/cm{sup 3}. The mannequin was put instead of the patient, inside the treatment room and the spectra and absorbed dose were determined by photo-neutrons exposed to a Linac of 15 MV. (Author)
Energy Technology Data Exchange (ETDEWEB)
Silva, Marcelo Vilela da; Fontes, Gladson Silva; Cardoso, Domingos D’Oliveira, E-mail: marcelovilelasilva@gmail.com [Instituto Militar de Engenharia (IME), Rio de Janeiro, RJ (Brazil)
2017-07-01
Particle technology has a profound impact on society. Its applications are well established mainly in the treatment of cancer and other diseases. The objective of this work was to develop an experimental apparatus with {sup 3}He detectors for photoneutron measurements greater than 8 MV. The apparatus allowed to obtain a multi energetic neutron measurements with detector and changing the different thicknesses of shields and for different dose rates. Additionally, an analytical model was developed, based on the approximation of the diffusion, for two groups of energy. The results indicated an increasing and linear behavior in the detector response. (author)
International Nuclear Information System (INIS)
Ulmer, Paul E.
1998-01-01
This grant covers the period Sept. 1, 1994 to Aug. 31, 1996 with an extension to Dec. 31, 1996. The main activities funded by this research grant include work on the TJNAF (formerly CEBAF) Hall A data analysis software project and other projects in Hall A worked on by my graduate students. All of these projects are necessary for the functioning of Hall A and are therefore directly related to my Hall A research program. The Hall A experimental equipment is still in the commissioning phase with the first experiment expected to be performed in May of 1997. My effort has focused on software development, in particular on analyzing and calibrating the vertical drift chambers (VDCs) which will be used for particle tracking in the high resolution spectrometers. I have written a standalone program to determine calibration constants needed to obtain the ultimate position and angle resolution. High resolution performance will be paramount for much of the Hall A experimental program. In particular, I am spokesman on an experiment to separate the response functions in the d(e,eprimep)n reaction. In order to make meaningful comparisons with theory, this experiment requires accurate determination of the cross sections and it will therefore be crucial to obtain the ultimate performance from the VDCs
Transitional nuclei near shell closures
Energy Technology Data Exchange (ETDEWEB)
Mukherjee, G. [Variable Energy Cyclotron Centre, 1/AF Bidhan Nagar, Kolkata 700064 (India); Pai, H. [Variable Energy Cyclotron Centre, 1/AF Bidhan Nagar, Kolkata 700064, India and Present Address: Institut für Kernphysik, Technische Universität Darmstadt, Schlossgartenstrasse 9, 64289 Darmstadt (Germany)
2014-08-14
High spin states in Bismuth and Thallium nuclei near the Z = 82 shell closure and Cesium nuclei near the N = 82 shell closure in A = 190 and A = 130 regions, respectively, have been experimentally investigated using heavy-ion fusion evaporation reaction and by detecting the gamma rays using the Indian National Gamma Array (INGA). Interesting shape properties in these transitional nuclei have been observed. The results were compared with the neighboring nuclei in these two regions. The total Routhian surface (TRS) calculations have been performed for a better understanding of the observed properties. In mass region A = 190, a change in shape from spherical to deformed has been observd around neutron number N = 112 for the Bi (Z = 83) isotopes with proton number above the magic gap Z = 82, whereas, the shape of Tl (Z = 81) isotopes with proton number below the magic gap Z = 82 remains stable as a function of neutron number. An important transition from aplanar to planar configuration of angular momentum vectors leading to the occurance of nuclar chirality and magnetic rotation, respectively, has been proposed for the unique parity πh{sub 11/2}⊗νh{sub 11/2} configuration in Cs isotopes in the mass region A ∼ 130 around neutron number N = 79. These results are in commensurate with the TRS calculations.
Cluster structure in Cf nuclei
International Nuclear Information System (INIS)
Singh, Shailesh K.; Biswal, S.K.; Bhuyan, M.; Patra, S.K.; Gupta, R.K.
2014-01-01
Due to the availability of advance experimental facilities, it is possible to probe the nuclei upto their nucleon level very precisely and analyzed the internal structure which will help us to resolve some mysterious problem of the decay of nuclei. Recently, the relativistic nuclear collision, confirmed the α cluster type structure in the 12 C which is the mile stone for the cluster structure in nuclei. The clustering phenomena in light and intermediate elements in nuclear chart is very interesting. There is a lot of work done by our group in the clustering behaviour of the nuclei. In this paper, the various prospectus of clustering in the isotopes of Cf nucleus including fission state is discussed. Here, 242 Cf isotope for the analysis, which is experimentally known is taken. The relativistic mean field model with well established NL3 parameter set is taken. For getting the exact ground state configuration of the isotopes, the calculation for minimizing the potential energy surface is performed by constraint method. The clustering structure of other Cf isotopes is discussed
Nuclear astrophysics of light nuclei
DEFF Research Database (Denmark)
Fynbo, Hans Otto Uldall
2013-01-01
A review of nuclear astrophysics of light nuclei using radioactive beams or techniques developed for radioactive beams is given. We discuss Big Bang nucleosynthesis, with special focus on the lithium problem, aspects of neutrino-physics, helium-burning and finally selected examples of studies...
Particle detection from oriented nuclei
International Nuclear Information System (INIS)
Wouters, J.; Moor, P. de; Schuurmans, P.; Severijns, N.; Vanderpoorten, W.; Vanneste, L.
1992-01-01
A survey is given of particle emission from nuclei that have been spin oriented by cryogenical means. Experiments and recent developments with detectors in the low temperature environment and their on-line application are reviewed. The most recent results are mentioned. Some phenomena to be unraveled in future studies are pointed out. (orig.)
Rotational damping motion in nuclei
International Nuclear Information System (INIS)
Egido, J.L.; Faessler, A.
1991-01-01
The recently proposed model to explain the mechanism of the rotational motion damping in nuclei is exactly solved. When compared with the earlier approximative solution, we find significative differences in the low excitation energy limit (i.e. Γ μ 0 ). For the strength functions we find distributions going from the Wigner semicircle through gaussians to Breit-Wigner shapes. (orig.)
Percolation and multifragmentation of nuclei
International Nuclear Information System (INIS)
Shmakov, S.Yu.; Uzhinskij, V.V.
1989-01-01
A method to build the 'cold' nuclei as percolation clusters is suggested. Within the framework of definite assumptions of the character of nucleon-nucleon couplings breaking resulting from the nuclear reactions as description of the multifragmentation process in the hadron-nucleus and nucleus-nucleus reactions at high energies is obtained. 19 refs.; 6 figs
Octupole correlation effects in nuclei
International Nuclear Information System (INIS)
Chasman, R.R.
1992-01-01
Octupole correlation effects in nuclei are discussed from the point of view of many-body wavefunctions as well as mean-field methods. The light actinides, where octupole effects are largest, are considered in detail. Comparisons of theory and experiment are made for energy splittings of parity doublets; E1 transition matrix elements and one-nucleon transfer reactions
Electron scattering for exotic nuclei
Indian Academy of Sciences (India)
2014-11-04
Nov 4, 2014 ... A brand-new electron scattering facility, the SCRIT Electron Scattering Facility, will soon start its operation at RIKEN RI Beam Factory, Japan. This is the world's first electron scattering facility dedicated to the structure studies of short-lived nuclei. The goal of this facility is to determine the charge density ...
Cross sections for atmospheric corrections
International Nuclear Information System (INIS)
Meyer, J.P.; Casse, M.; Westergaard, N.
1975-01-01
A set of cross sections for spallation of relativistic nuclei is proposed based on (i) the best available proton cross sections, (ii) an extrapolation to heavier nuclei of the dependence on the number of nucleons lost of the 'target factor' observed for C 12 and O 16 by Lindstrom et al. (1975), in analogy with Rudstam's formalism, and (iii) on a normalization of all cross sections to the total cross sections for production of fragments with Asub(f) >= 6. The obtained cross sections for peripheral interactions are not inconsistent with simple geometrical considerations. (orig.) [de
Real and virtual pions in nuclei
International Nuclear Information System (INIS)
Giraud, N.
1984-02-01
The thesis first part is concerned with physical pion interaction with deuton, studied in a three-body problem frame. The elastic cross-section in the energy range near the resonance (3-3), has been deduced taking in account the pion virtual absorption. The second part is concerned with virtual pion in nuclei. In particular the virtual pion cloud around the nucleus has been studied and the effective constant coupling pion-nucleus has been deduced. This one is strongly reduced by polorazation effects of the nuclear medium (essentially by virtual excitation of the Δ isobar), in relation to its value for free nucleon collection. In the frame of the same polarization model, the pion field inside the nucleus has been studied also. This field is lowered for small momentum transfer. It is increased for large momentum transfer. This last phenomenon corresponds to critical opalescence related to phase transition of pion condensation [fr
The resonance neutron fission on heavy nuclei
International Nuclear Information System (INIS)
Kopach, Yu.N.; Popov, A.B.; Furman, V.I.; Alfimenkov, V.P.; Lason', L.; Pikel'ner, L.B.; ); Gonin, N.N.; Kozlovskij, L.K.; Tambovtsev, D.I.; Gagarskij, A.M.; Petrov, G.A.; Sokolov, V.E.
2001-01-01
A new approach to the description of the fission, similar to the well-known reaction theory and based on the helicity representation for the exit fission channels, is briefly summarized. This approach allows one to connect the multimodal fission representation with A. Bohr's concept of the fission transition states and to obtain formulae for the partial and differential fission cross sections. The formulae are used for analysis of the angular anisotropy of fragments in the neutron resonance induced fission of aligned 235 U nuclei and of the P-even angular forward-backward and right-left correlations of fragments oe the P-odd correlations caused by the interference of s- and p-wave neutron resonances [ru
On rescattering in meson coherent photoproduction on nuclei
International Nuclear Information System (INIS)
Starkov, N.I.; Tsarev, V.A.
1978-01-01
Screening corrections for cross section of π deg-meson photoproduction on He nuclei were calculated: γ + 4 He → π 0 + 4 He. On the basis of the Glauber theory the effect of meson rescattering in the range of small transferred pulses (t) 2 and ''mean'' photon energies 2 2 ), determined by interference of members of one-and twofold interactions. The results are compared with those obtained by other authors
Resonances in collisions between S-D shell nuclei
International Nuclear Information System (INIS)
Betts, R.R.
1984-01-01
Experimental evidence relating to the existence of resonances in collisions between s-d shell nuclei will be reviewed. The determination of the spins and spectroscopic properties of some of these resonances will be discussed. The behaviour of both the resonance and background cross-sections will be compared with model expectations. Some future directions in this area of study will be indicated and the relationship of this work to other results briefly discussed. (author)
Three-dimensional TDHF calculation for reactions of unstable nuclei
Energy Technology Data Exchange (ETDEWEB)
Kim, Ka-Hae; Otsuka, Takaharu [Tokyo Univ. (Japan). Dept. of Physics; Bonche, P.
1998-07-01
The fusion is studied for reactions between a stable and an unstable nuclei with neutron skin. The reactions {sup 16,28}O+{sup 40}Ca and {sup 16}O+{sup 16,28}O are taken as examples, and the three-dimensional time-dependent Hartree-Fock method with the full Skyrme interaction is used. It is confirmed that the fusion cross section in low-energy region is sensitive to the interaction used in the calculation. (author)
Reactions probing effects of quark clusters in nuclei
International Nuclear Information System (INIS)
Lassila, K.E.; Sukhatme, U.P.
1988-01-01
We study signatures of quark clusters in reactions which probe quarks in nuclei. We examine the EMC effect and use physical arguments to establish features of valence and ocean parton distributions in multiquark clusters. We predict from these distributions ratios of structure functions and cross sections measured with neutrino, antineutrinos and proton beams. It appears that a unique determination of the source of the EMC effect will be possible. 6 refs., 4 figs
International Nuclear Information System (INIS)
Hartwig, S.; Heimlich, F.H.; Huber, G.; Roessle, E.; Koebberling, M.; Moritz, J.; Schmidt, K.H.; Wegener, D.; Zeller, D.; Karlsruhe Univ.; Bleckwenn, J.
1977-08-01
The cross section for inelastic electron scattering on 12 C and 27 Al nuclei has been measured for energy transfers of the virtual photon 2 . The influence of different sources of the radiative corrections is studied in detail. Shadowing effects, which increase with decreasing values of the scalling variable x, are observed for both nuclei. (orig.) [de
/sup 12/C(γ,n) cross section from 30 to 100 MeV
International Nuclear Information System (INIS)
Harty, P.D.; Thompson, M.N.; O'Keefe, G.J.
1988-01-01
This paper reports a measurement of the differential photoneutron cross section of /sup 12/C at 65 0 , between E/sub γ/ = 30 and 100 MeV. Tagged photons, monochromatic to within 2.6 MeV, were used, thus allowing the cross sections to a wide range of final states to be observed. The results are compared to the photoproton cross section of /sup 12/C, which was measured previously, under similar conditions. Comparisons are also made with calculations based on the quasi-deuteron model, and with calculations by Gari and Hebach, and Cavinato et al. These latter calculations incorporate two-body effects by the inclusion of meson exchange currents. The agreement between these calculations and the measured cross section is in contrast to predictions of a direct, single-nucleon knockout model of the reaction mechanism, indicating the importance of two-body effects in the photoreaction process for energies greater than 50 MeV
Cavitation nuclei measurements - A review
International Nuclear Information System (INIS)
Billet, M.L.
1985-01-01
The measurement of cavitation nuclei has been the goal of many cavitation research laboratories and has resulted in the development of many methods. Two significantly different approaches have been developed. One is to measure the particulate-microbubble distribution by utilizing acoustical, electrical or optical methods. The other approach measures a liquid tension and a rate of cavitation events for a liquid in order to establish a cavitation susceptibility. Comparisons between various methods indicate that most methods are capable of giving an indication of the nuclei distribution. Measurements obtained in the ocean environment indicate an average of three bubbles per cubic centimeter are present; whereas, water tunnel bubble distributions vary from much less than one to over a hundred per cubic centimeter
Phonon operators in deformed nuclei
International Nuclear Information System (INIS)
Soloviev, V.G.
1981-01-01
For the description of the excited states in deformed nuclei new phonon operators are introduced, which depend on the sign of the angular momentum projection onto the symmetry axis of a deformed nucleus. In the calculations with new phonons the Pauli principle is correctly taken into account in the two-phonon components of the wave functions. There is a difference in comparison with the calculation with phonons independent of the sign of the angular momentum projection. The new phonons should be used in deformed nuclei if the Pauli principle is consistently taken into account and in the calculations with the excited state wave functions having the components with more than one phonon operator [ru
Phonon operators for deformed nuclei
International Nuclear Information System (INIS)
Solov'ev, V.G.
1982-01-01
The mathematical formalism with the phonon operators independent of the signature of the angular momentum projection turns out to be inadequate for describing excited states of deformed nuclei. New phonon operators are introduced which depend on the signature of the angular momentum projection on the symmetry axis of a deformed nucleus. It is shown that the calculations with the new phonons take correctly into account the Pauli principle in two-phonon components of wave functions. The results obtained differ from those given by the phonons independent of the signature of the angular momentum projection. The new phonons must be used in deformed nuclei at taking systematically the Pauli principle into account and in calculations involving wave functions of excited states having components with more than one-phonon operator
Nuclear treasure island [superheavy nuclei
CERN. Geneva
1999-01-01
Summary form only given. Soon after the experiments at Dubna, which synthesized element 114 and made the first footprints on the beach of the "island of nuclear stability", two new superheavy elements have been discovered at the Lawrence Berkeley National Laboratory. Element 118 and its immediate decay product, element 116, were manufactured at Berkeley's 88 inch cyclotron by fusing targets of lead-208 with an intense beam of 449 MeV krypton-86 ions. Although both new nuclei almost instantly decay into lighter ones, the decay sequence is consistent with theories that have long predicted the island of stability for nuclei with approximately 114 protons and 184 neutrons. Theorist Robert Smolanczuk, visiting from the Soltan Institute for Nuclear Studies in Poland, had calculated that this reaction should have particularly favourable production rates. Now that this route has been signposted, similar reactions could be possible: new elements and isotopes, tests of nuclear stability and mass models, and a new under...
Moessbauer effects on oriented nuclei
International Nuclear Information System (INIS)
Sayouti, E.H.
1984-01-01
Standard nuclear orientation methods (not sensitive to the polarization) do not give information on the sign of the magnetic moment. Mossbauer effect separates right-hand and left-hand circularly polarized components, thus its detection on oriented nuclei (T approximately 10 mK) gives the sign of the magnetic moment of oriented state. In this thesis we applied this method to study the 3/2 - ground states of 191 Pt and 193 Os, which are in the prolate-oblate transition region, where assignement of experimental levels to theoretical states is often umbiguous. We show that for those nuclei the sign of the magnetic moment is the signature of the configuration, and its determination establishes the correspondance between experimental and theoretical levels [fr
International Nuclear Information System (INIS)
Beck, Christian
2010-01-01
Following the pioneering discovery of alpha clustering and of molecular resonances, the field of nuclear clustering is presently one of the domains of heavy-ion nuclear physics facing both the greatest challenges and opportunities. After many summer schools and workshops, in particular over the last decade, the community of nuclear molecular physics decided to team up in producing a comprehensive collection of lectures and tutorial reviews covering the field. This first volume, gathering seven extensive lectures, covers the follow topics: - Cluster Radioactivity - Cluster States and Mean Field Theories - Alpha Clustering and Alpha Condensates - Clustering in Neutron-rich Nuclei - Di-neutron Clustering - Collective Clusterization in Nuclei - Giant Nuclear Molecules By promoting new ideas and developments while retaining a pedagogical nature of presentation throughout, these lectures will both serve as a reference and as advanced teaching material for future courses and schools in the fields of nuclear physics and nuclear astrophysics. (orig.)
International Nuclear Information System (INIS)
Oset, E.
1980-01-01
A short review of the topic of mesons in nuclei is exposed paying particular attention to the relationship between several mesonic processes. Special emphasis is put into the microscopic pictures that can ultimately relate all these processes with the elementary coupling of mesons to the nuclear hadronic components. The importance of the short range part of the nuclear interaction opens the doors to a more basic understanding in terms of the quark components of nucleons and isobars. (orig.)
Exclusive photoreactions on light nuclei
International Nuclear Information System (INIS)
Maruyama, K.
1989-08-01
The mechanism of photon absorption on light nuclei in the Δ-resonance region is discussed. The present status of experimental results is briefly summarized. A recent data from 1.3-GeV Tokyo ES using a π sr spectrometer is introduced. Exclusive measurements of the photodisintegration of 3 He and 4 He may be a clear way to identify 2N, 3N and 4N absorptions. (author)
Fission barriers of light nuclei
International Nuclear Information System (INIS)
Grotowski, K.; Planeta, R.; Blann, M.; Komoto, T.
1989-01-01
Experimental fission excitation functions for compound nuclei /sup 52/Fe, /sup 49/Cr, /sup 46/V, and /sup 44/Ti formed in heavy-ion reactions are analyzed in the Hauser-Feshbach/Bohr-Wheeler formalism using fission barriers based on the rotating liquid drop model of Cohen et al. and on the rotating finite range model of Sierk. We conclude that the rotating finite range approach gives better reproduction of experimental fission yields, consistent with results found for heavier systems
International Nuclear Information System (INIS)
Armbruster, P.; Hessberger, F.P.
1998-01-01
In the last 60 years physicists have created 20 artificial elements beyond uranium. In 1934 Enrico Fermi predicted the creation of new elements by bombarding atoms with neutrons. This method led to the discovery of neptunium (Z=93), plutonium, americium, curium, berkelium, californium, einsteinium and fermium (Z=100). In fact the capture of a neutron is followed by a beta-decay which increases the atomic number (Z) by one unit. Beyond Z=100 beta-decay no more occurs so a new approach was necessary. Between the American Lawrence Berkeley Laboratory and the Russian Dubna Institute a fierce competition broke out to produce new elements by bombarding transuranium nuclei with light elements such as helium, carbon, nitrogen. This new method required heavy equipment: ion accelerator and detectors but led to the creation of all the elements from Z=101 to Z=106. A new idea was to provoke the fusion of heavy nuclei such as lead and bismuth with colliding argon, nickel or zinc ion beams. This method called 'cold fusion' opened the way to reach the nuclei beyond Z=107. In 1996 the element Z=112 was the last discovered. The next step could be the element Z=114 for which a particular stability is expected. (A.C.)
Thermodynamical description of excited nuclei
International Nuclear Information System (INIS)
Bonche, P.
1989-01-01
In heavy ion collisions it has been possible to obtain composite systems at rather high excitation energies corresponding to temperatures of several MeV. The theoretical studies of these systems are based on concepts borrowed from thermodynamics or statistical physics, such as the temperature. In these lectures, we present the concepts of statistical physics which are involved in the physics of heavy ion as they are produced nowadays in the laboratory and also during the final stage of a supernova collapse. We do not attempt to describe the reaction mechanisms which yield such nuclear systems nor their decay by evaporation or fragmentation. We shall only study their static properties. The content of these lectures is organized in four main sections. The first one gives the basic features of statistical physics and thermodynamics necessary to understand quantum mechanics at finite temperature. In the second one, we present a study of the liquid-gas phase transition in nuclear physics. A phenomenological approach of the stability of hot nuclei follows. The microscopic point of view is proposed in the third part. Starting from the basic concepts derived in the first part, it provides a description of excited or hot nuclei which confirms the qualitative results of the second part. Furthermore it gives a full description of most properties of these nuclei as a function of temperature. Finally in the last part, a microscopic derivation of the equation of state of nuclear matter is proposed to study the collapse of a supernova core
Exotic Nuclei and Yukawa's Forces
International Nuclear Information System (INIS)
Otsuka, Takaharu; Suzuki, Toshio; Utsuno, Yutaka
2008-01-01
In this plenary talk, we will overview the evolution of the shell structure in stable and exotic nuclei as a new paradigm of nuclear structure physics. This shell evolution is primarily due to the tensor force. The robust mechanism and some examples will be presented. Such examples include the disappearance of existing magic numbers and the appearance of new ones. The nuclear magic numbers have been believed, since Mayer and Jensen, to be constants as 2, 8, 20, 28, 50, ... This turned out to be changed, once we entered the regime of exotic nuclei. This shell evolution develops at many places on the nuclear chart in various forms. For example, superheavy magic numbers may be altered. Thus, we are led to a new paradigm as to how and where the nuclear shell evolves, and what consequences arise. The evolution of the shell affects weak process transitions, and plays a crucial role in deformation. The π and ρ mesons generate tensor forces, and are the fundamental elements of such intriguing phenomena. Thus, physics of exotic nuclei arises as a manifestation of Yukawa's forces
Modelisation of the fission cross section
International Nuclear Information System (INIS)
Morariu, Claudia
2013-03-01
The neutron cross sections of four nuclear systems (n+ 235 U, n+ 233 U, n+ 241 Am and n+ 237 Np) are studied in the present document. The target nuclei of the first case, like 235 U and 239 Pu, have a large fission cross section after the absorption of thermal neutrons. These nuclei are called 'fissile' nuclei. The other type of nuclei, like 237 Np and 241 Am, fission mostly with fast neutrons, which exceed the fission threshold energy. These types of nuclei are called 'fertile'. The compound nuclei of the fertile nuclei have a binding energy higher than the fission barrier, while for the fissile nuclei the binding energy is lower than the fission barrier. In this work, the neutron induced cross sections for both types of nuclei are evaluated in the fast energy range. The total, reaction and shape-elastic cross sections are calculated by the coupled channel method of the optical model code ECIS, while the compound nucleus mechanism are treated by the statistical models implemented in the codes STATIS, GNASH and TALYS. The STATIS code includes a refined model of the fission process. Results from the theoretical calculations are compared with data retrieved from the experimental data base EXFOR. (author) [fr
Critical angular momentum dependence of the fission barriers and the stability of superheavy nuclei
International Nuclear Information System (INIS)
Magda, M.T.; Sandulescu, A.
1978-10-01
Measured complete fusion and evaporation cross section data are used to determine the critical angular momenta for which the fission barriers are vanishing in the region of nuclei with Z = 102 - 116. It is shown that, in order to fit these data, larger values of the critical angular momenta are obtained for superheavy nuclei (Z = 110 - 112) than for heavy ones (Z = 102 - 107), which indicates a relatively higher stability against fission for superheavy nuclei, in agreement with the theoretically predicted island of stability. (author)
Energy Technology Data Exchange (ETDEWEB)
Nakamura, T.; Kondo, Y.
2016-06-01
Large acceptance spectrometers at in-flight RI separators have played significant roles in investigating the structure of exotic nuclei. Such spectrometers are in particular useful for probing unbound states of exotic nuclei, using invariant mass spectroscopy with reactions at intermediate and high energies. We discuss here the key characteristic features of such spectrometers, by introducing the recently commissioned SAMURAI facility at the RIBF, RIKEN. We also investigate the issue of cross talk in the detection of multiple neutrons, which has become crucial for exploring further unbound states and nuclei beyond the neutron drip line. Finally we discuss future perspectives for large acceptance spectrometers at the new-generation RI-beam facilities.
The colours of Hubble Sc galaxy nuclei
International Nuclear Information System (INIS)
Iskudaryan, S.G.
1975-01-01
The colorimetric data on the nuclei of the Sc galaxies are given. Comparison of the following parameters: color of a nucleus, integral color of a galaxy, Byurakan class, and spectral type of normal spirals gives the possibility to conclude: (1) The colors of the nuclei of the Sc galaxies have a high dispersion in its values. In all Byurakan classes the galaxies with intensely red and blue nuclei occur; (2) Some Sc galaxies exhibit a discrepancy between the spectral and morphological types. The results of colorimetry of nuclei indicate that almost all such Sc galaxies have intensely red nuclei which, naturally, provide for these late spectral types. It can be assumed that the intensely red color of the nuclei of such Sc galaxies is a result of a new type of activity of these nuclei; and (3) some Sc galaxies show the characteristics of the Markarian objects
On the theory of deuteron disintegration with collective states excitation in nuclei
International Nuclear Information System (INIS)
Evlanov, M.V.
1981-01-01
Differential cross sections of diffraction disintegration of deuterons with excitation of collective states in nuclei have been theoretically investigated. Effects of nucleon-nucleon interaction as well as smearing of nucleus boundary on differential characteristics of deuteron disintegration accompanying with change in state of target- nuclei have been studied. Spectra of protons liberated during the reaction of 2 + level deuteron disintegration in 114 Cd nucleus are presented [ru
Microscopic approach to the theory of light nuclei and to simple nuclear reactions
International Nuclear Information System (INIS)
Baz', L.I.; Filippov, G.F.
1976-01-01
The results of calculations for the properties of light nuclei and simple nuclear reactions using the Schrodinger multinucleon equation involving the realistic nucleon-nucleon interaction are reviewed. It is noted that the theory for the A(<=)4 nuclei is practically complete at present. The reasons for the good agreement between the theoretical and experimental cross sections of nuclear reactions are given. The programme of a correct separation of the nuclear collective degree of freedom are discussed in detail
Dynamic deformation theory of spherical and deformed light and heavy nuclei with A = 12-240
International Nuclear Information System (INIS)
Kumar, Krishna.
1979-01-01
Deformation dependent wave functions are calculated for different types of even-even nuclei (spherical, transitional, deformed; light, medium, heavy) without any fitting parameters. These wave functions are employed for the energies, B(E2)'s, quadrupole and magnetic moments of selected nuclei with A = 12-240 (with special emphasis on 56 Fe, 154 Gd), and for neutron cross sections of 148 Sm, 152 Sm
Disintegration of Ta and W nuclei by high-energy electrons and photons
International Nuclear Information System (INIS)
Mitrofanova, A.V.; Noga, V.I.; Popov, A.I.; Ranyuk, Yu.N.; Telegin, Yu.N.
1977-01-01
The induced activity method is applied to measure the yields of 15 photonuclear reactions on the tantalum and tungsten nuclei in the 600-1300 MeV energy range of photons. The cross sections are calculated in the ''rectangular'' approximation of the bremsstrahlung spectrum. The data are analysed by the Rudstam semiempirical formula. For the reactions with tungsten nuclei the photo- to electro-yield ratios are measured
On Coulomb disintegration of relativistic nuclei and hypernuclei
International Nuclear Information System (INIS)
Lyuboshits, V.L.
1989-01-01
The dependence of the total cross-section of excitation and disintegration of a relativistic nucleus in the Coulomb field on the energy and parameters characterizing nuclear dimensions is investigated. The analogy with the problem of atomic ionization at the passage of charged particles through matter is used. The results are applied to the description of the Coulomb dissociation of nuclei with small binding energies. An explicit expression for the effective cross-section of the Coulomb disintegration of the hypernucleus-Λ 3 H into a deuteron and Λ-particle. 12 refs
Deep inelastic collisions between very heavy nuclei
International Nuclear Information System (INIS)
Sann, H.; Olmi, A.; Civelekoglu, Y.
1977-01-01
A systematic survey of deep inelastic reactions was performed for colliding nuclei of masses between 80 and 240 amu. The application of large surface detectors and, particularly, of a position sensitive ionization chamber, has proved to be very effective and appropriate for this type of investigation. The Wilczynski diagrams describing the relative motion between the colliding objects shows a gradual trend as a function of growing masses of target and projectile where the trajectories lead the particles not toward negative scattering angles but increasingly into the direction around and above the grazing angle. This behavior is attributed to a delicate balance between Coulomb and nuclear forces. The energy dumping as a function of the mass transfer strength matches a general law between total kinetic energy loss and the variance of the proton number distribution. For the partly damped component this relation seems to hold independently from the choice of ingoing channel and bombarding energy. The dissipation of the kinetic energy does not depend only on the relative velocity of the impinging nuclei, and the simple friction model is not appropriate to describe these processes. The γ-multiplicity measurement displays a rapid increase as a function of scattering angle and total kinetic energy loss, which give new insights to the process and indicate the necessity of microscopic quantum mechanical calculations of the interaction. In the U-U collision large mass transfers are present which possibly populate with relatively large cross sections the transuranic elements. In the Pb-Pb reaction the mass transfer is more restricted. The decay probability by fission of the primary masses increases strongly for growing masses and excitation energies
Cold transfer between deformed, Coulomb excited nuclei
International Nuclear Information System (INIS)
Bauer, H.
1998-01-01
The scattering system 162 Dy → 116 Sn has been examined at energies in the vicinity of the Coulomb barrier using the Heidelberg-Darmstadt Crystal Ball spectrometer combined with 5 Germanium-CLUSTER detectors. In order to study pairing correlations as a function of angular momentum cold events were selected in the 2n stripping channel by identifying and suppressing the dominant hot part of the transfer with the Crystal Ball. The CLUSTER detectors with their high γ-efficiency were used to identify the transfer channel and to resolve individual final states. Cross sections for the population of individual yrast states in a cold transfer reaction have been measured for the first time indicating the strong influence of higher transfer multipolarities. At small surface distances Coulomb-nuclear interferences were found to be responsible for the stronger decline of the population of higher yrast states in the transfer channel as compared to the Coulex channel. As a preparatory study for 2n transfer measurements between high spin yrast states in the backbending region of deformed nuclei the Coulomb excitation process in the crossing region of two bands in 162 Dy has been analyzed. The gross properties of the measured population probabilities could be interpreted in a simple band mixing model. (orig.)
International Nuclear Information System (INIS)
Luo, Junhua; Feng, Zhifu; An, Li; Jiang, Li; He, Long
2016-01-01
Activation cross-sections for the 162 Dy(n,p) 162 Tb and 163 Dy(n,p) 163 Tb reactions have been measured by means of the activation technique and a coaxial HPGe γ-ray detector at 13.5 and 14.8 MeV. The fast neutrons were produced via the 3 H(d,n) 4 He reaction on Pd-300 neutron generator. The natural high-purity Dy 2 O 3 powder was used as target material. Theoretical excitation functions were calculated using the nuclear-reaction codes EMPIRE-3.2 Malta and TALYS-1.6 with default parameters, at neutron energies varying from the reaction threshold to 20 MeV. The results were also discussed and compared with some corresponding values found in the literature, with the comprehensive evaluation data in ENDF/B-VII.1 and JENDF-4.0 libraries, and with the estimates obtained from a published empirical formula based on the statistical model with Q-value dependence and odd–even effects taken into consideration. - Highlights: • The cross sections for the 162 Dy(n,p) 162 Tb and 163 Dy(n,p) 163 Tb have been measured. • 93 Nb(n,2n) 92m Nb was used as a monitor for neutron fluence. • Codes TALYS-1.6 and EMPIRE-3.2 Malta were used to model the reactions. • The results were compared with previous data. • Inconsistency with previous data and with model calculations are noted.
Spectroscopy of few-particle nuclei around magic 132Sn from fission product γ-ray studies
International Nuclear Information System (INIS)
Zhang, C. T.
1998-01-01
We are studying the yrast structure of very neutron-rich nuclei around doubly magic 132 Sn by analyzing fission product γ-ray data from a 248 Cm source at Eurogam II. Yrast cascades in several few-valence-particle nuclei have been identified through γγ cross coincidences with their complementary fission partners. Results for two-valence-particle nuclei 132 Sb, 134 Te, 134 Sb and 134 Sn provide empirical nucleon-nucleon interactions which, combined with single-particle energies already known in the one-particle nuclei, are essential for shell-model analysis in this region. Findings for the N = 82 nuclei 134 Te and 135 I have now been extended to the four-proton nucleus 136 Xe. Results for the two-neutron nucleus 134 Sn and the N = 83 isotones 134 Sb, 135 Te and 135 I open up the spectroscopy of nuclei in the northeast quadrant above 132 Sn
[Fast neutron cross section measurements
International Nuclear Information System (INIS)
Knoll, G.F.
1992-01-01
From its inception, the Nuclear Data Project at the University of Michigan has concentrated on two major objectives: (1) to carry out carefully controlled nuclear measurements of the highest possible reliability in support of the national nuclear data program, and (2) to provide an educational opportunity for students with interests in experimental nuclear science. The project has undergone a successful transition from a primary dependence on our photoneutron laboratory to one in which our current research is entirely based on a unique pulsed 14 MeV fast neutron facility. The new experimental facility is unique in its ability to provide nanosecond bursts of 14 MeV neutrons under conditions that are ''clean'' and as scatter-free as possible, and is the only one of its type currently in operation in the United States. It has been designed and put into operation primarily by graduate students, and has met or exceeded all of its important initial performance goals. We have reached the point of its routine operation, and most of the data are now in hand that will serve as the basis for the first two doctoral dissertations to be written by participating graduate students. Our initial results on double differential neutron cross sections will be presented at the May 1993 Fusion Reactor Technology Workshop. We are pleased to report that, after investing several years in equipment assembly and optimization, the project has now entered its ''data production'' phase
Inclusive breakup of three-fragment weakly bound nuclei
International Nuclear Information System (INIS)
Carlson, B.V.; Frederico, T.; Hussein, M.S.
2017-01-01
The inclusive breakup of three-fragment projectiles is discussed within a four-body spectator model. Both the elastic breakup and the non-elastic breakup are obtained in a unified framework. Originally developed in the 80's for two-fragment projectiles such as the deuteron, in this paper the theory is successfully generalized to three-fragment projectiles. The expression obtained for the inclusive cross section allows the extraction of the incomplete fusion cross section, and accordingly generalizes the surrogate method to cases such as (t, p) and (t, n) reactions. It is found that two-fragment correlations inside the projectile affect in a conspicuous way the elastic breakup cross section. The inclusive non-elastic breakup cross section is calculated and is found to contain the contribution of a three-body absorption term that is also strongly influenced by the two-fragment correlations. This latter cross section contains the so-called incomplete fusion where more than one compound nuclei are formed. Our theory describes both stable weakly bound three-fragment projectiles and unstable ones such as the Borromean nuclei.
Inclusive breakup of three-fragment weakly bound nuclei
Energy Technology Data Exchange (ETDEWEB)
Carlson, B.V.; Frederico, T. [Instituto Tecnológico de Aeronáutica, DCTA, 12.228-900 São José dos Campos, SP (Brazil); Hussein, M.S., E-mail: hussein@if.usp.br [Instituto Tecnológico de Aeronáutica, DCTA, 12.228-900 São José dos Campos, SP (Brazil); Instituto de Estudos Avançados, Universidade de São Paulo, C.P. 72012, 05508-970 São Paulo, SP (Brazil); Instituto de Física, Universidade de São Paulo, C.P. 66318, 05314-970 São Paulo, SP (Brazil)
2017-04-10
The inclusive breakup of three-fragment projectiles is discussed within a four-body spectator model. Both the elastic breakup and the non-elastic breakup are obtained in a unified framework. Originally developed in the 80's for two-fragment projectiles such as the deuteron, in this paper the theory is successfully generalized to three-fragment projectiles. The expression obtained for the inclusive cross section allows the extraction of the incomplete fusion cross section, and accordingly generalizes the surrogate method to cases such as (t, p) and (t, n) reactions. It is found that two-fragment correlations inside the projectile affect in a conspicuous way the elastic breakup cross section. The inclusive non-elastic breakup cross section is calculated and is found to contain the contribution of a three-body absorption term that is also strongly influenced by the two-fragment correlations. This latter cross section contains the so-called incomplete fusion where more than one compound nuclei are formed. Our theory describes both stable weakly bound three-fragment projectiles and unstable ones such as the Borromean nuclei.
Exotic light nuclei and nuclei in the lead region
International Nuclear Information System (INIS)
Poppelier, N.A.F.M.
1989-01-01
Three methods are discussed for modifying, or renormalizing, a truncated nuclear hamiltonian such that the wave functions obtained by diagonalizing this modified or effective hamiltoniandescribe the nucleus as well as possible: deriving the hamiltonian directly from a realistic nucleon-nucleon interaction between free nucleons; parametrizing the hamiltonian in terms of a number of parameters and determining these parameters from a least-squares fit of calculated properties to experimental data; approximating the nucleon-nucleon (NN) interaction between two nucleons in a nucleus by a simple analytic expression. An effective hamiltonian derived following the second method is applied in a theoretical study of exotic nuclei in the region of Z=2-9 and A=4-30 and the problem of the neutron halo in 11 Li is discussed. Results of shell-model calculations of 20i Pb and nuclei in its neighbourhood are presented in which an effective hamiltonian was employed derived with the last method. The quenching of M1 strength in 208 Pb, and the spectroscopic factors measured in proton knock-out reactions could be described quite satisfactory. Finally, a method is presented for deriving the effective hamiltonian directly from the realistic NN interaction with algebraic techniques. (H.W.). 114 refs.; 34 figs.; 12 tabs.; schemes
Isospin mixing in light nuclei
International Nuclear Information System (INIS)
Ludwig, E.J.; Clegg, T.B.; Fauber, R.E.; Karwowski, H.J.; Mooney, T.M.; Thompson, W.J.
1985-01-01
This program has provided accurate measurements of isospin mixing (ΔT = 1,2) in proton elastic scattering on even-even target nuclei up to A = 40. In order to improve experimental results and to test the hypothesis that isospin mixing is dominated by mixing in the target ground state (as opposed to mixing in the compound system) the authors have undertaken to (1) extend the proton scattering results to additional T = 3/2 states in certain compound systems and (2) examine processes which can proceed by only isotensor mixing (ΔT = 2) in order to isolate the effects of that contribution
Nucleon transfer between heavy nuclei
International Nuclear Information System (INIS)
Von Oertzen, W.
1984-02-01
Nucleon transfer reactions between heavy nuclei are characterized by the classical behaviour of the scattering orbits. Thus semiclassical concepts are well suited for the description of these reactions. In the present contribution the characteristics of single and multinucleon transfer reactions at energies below and above the Coulomb barrier are shown for systems like Sn+Sn, Xe+U and Ni+Pb. The role of the pairing interaction in the transfer of nucleon pairs is illustrated. For strong transitions the coupling of channels and the absorption into more complicated channels is taken into account in a coupled channels calculation
Microscopic properties of superdeformed nuclei
Energy Technology Data Exchange (ETDEWEB)
Karlsson, Lennart B
1999-04-01
Many high spin rotational bands in superdeformed nuclei have been found in the A 140 - 150 region, but so far no linking transitions to known normal-deformed states have been found in these nuclei. Therefore, configuration and spin assignments have to be based on indirect spectroscopic information. Identical bands were first discovered in this region of superdeformed states. At present, some identical bands have also been found at normal deformation, but such bands are more common at superdeformation. Recently lifetime measurements have given relative quadrupole moments with high accuracy. Spectroscopic quantities are calculated using the configuration constrained cranked Nilsson-Strutinsky model with the modified oscillator potential. In a statistical study the occurrence of identical bands is tested. Comparing superdeformed and normal deformed nuclei, the higher possibility for identical bands at superdeformation is understood from calculated reduced widths of the E{sub {gamma}} and J{sup (2)} distributions. The importance of high-N orbitals for identical bands is also discussed. Additivity of electric quadrupole moment contributions in the superdeformed A - 150 region is discussed with the nucleus {sup 152}Dy as a `core`. In analytic harmonic oscillator calculations, the effective electric quadrupole moment q{sub eff}, i.e. the change in the total quadrupole moment caused by the added particle, is expressed as a simple function of the single-particle mass, quadrupole moment q{sub {nu}}. Also in realistic calculations, simple relations between q{sub eff} and q{sub {nu}} can be used to estimate the total electric quadrupole moment, e.g. for the nucleus {sup 142}Sm, by adding the effect of 10 holes, to the total electric quadrupole moment of {sup 152}Dy. Furthermore, tools are given for estimating the quadrupole moment for possible configurations in the superdeformed A - 150 region. For the superdeformed region around {sup 143}Eu, configuration and spin assignments
Remarks on the fission barriers of super-heavy nuclei
Energy Technology Data Exchange (ETDEWEB)
Hofmann, S. [GSI Helmholtzzentrum fuer Schwerionenforschung, Darmstadt (Germany); Goethe-Universitaet Frankfurt, Institut fuer Physik, Frankfurt (Germany); Heinz, S.; Mann, R.; Maurer, J.; Muenzenberg, G.; Barth, W.; Dahl, L.; Kindler, B.; Kojouharov, I.; Lang, R.; Lommel, B.; Runke, J.; Scheidenberger, C.; Tinschert, K. [GSI Helmholtzzentrum fuer Schwerionenforschung, Darmstadt (Germany); Antalic, S. [Comenius University, Department of Nuclear Physics and Biophysics, Bratislava (Slovakia); Eberhardt, K.; Thoerle-Pospiech, P.; Trautmann, N. [Johannes Gutenberg-Universitaet Mainz, Mainz (Germany); Grzywacz, R. [Oak Ridge National Laboratory, Oak Ridge, TN (United States); University of Tennessee, Knoxville, TN (United States); Hamilton, J.H. [Vanderbilt University, Department of Physics and Astronomy, Nashville, TN (United States); Henderson, R.A.; Kenneally, J.M.; Moody, K.J.; Shaughnessy, D.A.; Stoyer, M.A. [Lawrence Livermore National Laboratory, Livermore, CA (United States); Miernik, K. [Oak Ridge National Laboratory, Oak Ridge, TN (United States); University of Warsaw, Warsaw (Poland); Miller, D. [University of Tennessee, Knoxville, TN (United States); Morita, K. [RIKEN Nishina Center for Accelerator-Based Science, Wako, Saitama (Japan); Nishio, K. [Japan Atomic Energy Agency, Tokai, Ibaraki (Japan); Popeko, A.G.; Yeremin, A.V. [Joint Institute for Nuclear Research, Dubna (Russian Federation); Roberto, J.B.; Rykaczewski, K.P. [Oak Ridge National Laboratory, Oak Ridge, TN (United States); Uusitalo, J. [University of Jyvaeskylae, Department of Physics, Jyvaeskylae (Finland)
2016-04-15
Shell-correction energies of super-heavy nuclei are approximated by using Q{sub α} values of measured decay chains. Five decay chains were analyzed, which start at the isotopes {sup 285}Fl, {sup 294}118, {sup 291}Lv, {sup 292}Lv and {sup 293}Lv. The data are compared with predictions of macroscopic-microscopic models. Fission barriers are estimated that can be used to eliminate uncertainties in partial fission half-lives and in calculations of evaporation-residue cross-sections. In that calculations, fission probability of the compound nucleus is a major factor contributing to the total cross-section. The data also provide constraints on the cross-sections of capture and quasi-fission in the entrance channel of the fusion reaction. Arguments are presented that fusion reactions for synthesis of isotopes of elements 118 and 120 may have higher cross-sections than assumed so far. (orig.)
Three-body halo nuclei in an effective theory framework
Energy Technology Data Exchange (ETDEWEB)
Canham, David L.
2009-05-20
The universal properties and structure of halo nuclei composed of two neutrons (2n) and a core are investigated within an effective quantum mechanics framework. We construct an effective interaction potential that exploits the separation of scales in halo nuclei and treat the nucleus as an effective three-body system, which to leading order is described by the large S-wave scattering lengths in the underlying two-body subsystems. The uncertainty from higher orders in the expansion is quantified through theoretical error bands. First, we investigate the possibility to observe excited Efimov states in 2n halo nuclei. Based on the experimental data, {sup 20}C is the only halo nucleus candidate to possibly have an Efimov excited state, with an energy less than 7 keV below the scattering threshold. Second, we study the structure of {sup 20}C and other 2n halo nuclei. In particular, we calculate their matter density form factors, radii, and two-neutron opening angles. We then make a systematic improvement upon these calculations by extending the effective potential to the next-to-leading order. To this order, we require an additional two-body parameter, which we tune to the effective range of the interaction. In addition to range corrections to the 2n halo nuclei results, we show corrections to the Efimov effect in the three-boson system. Furthermore, we explore universality in the linear range corrections to the Efimov spectrum. Finally, we study the scattering of D{sup 0} and D{sup *0} mesons and their antiparticles off the X(3872) in an effective field theory for short-range interactions. We present results for the S-wave scattering amplitude, total interaction cross section and S-wave scattering length. (orig.)
Three-body halo nuclei in an effective theory framework
International Nuclear Information System (INIS)
Canham, David L.
2009-01-01
The universal properties and structure of halo nuclei composed of two neutrons (2n) and a core are investigated within an effective quantum mechanics framework. We construct an effective interaction potential that exploits the separation of scales in halo nuclei and treat the nucleus as an effective three-body system, which to leading order is described by the large S-wave scattering lengths in the underlying two-body subsystems. The uncertainty from higher orders in the expansion is quantified through theoretical error bands. First, we investigate the possibility to observe excited Efimov states in 2n halo nuclei. Based on the experimental data, 20 C is the only halo nucleus candidate to possibly have an Efimov excited state, with an energy less than 7 keV below the scattering threshold. Second, we study the structure of 20 C and other 2n halo nuclei. In particular, we calculate their matter density form factors, radii, and two-neutron opening angles. We then make a systematic improvement upon these calculations by extending the effective potential to the next-to-leading order. To this order, we require an additional two-body parameter, which we tune to the effective range of the interaction. In addition to range corrections to the 2n halo nuclei results, we show corrections to the Efimov effect in the three-boson system. Furthermore, we explore universality in the linear range corrections to the Efimov spectrum. Finally, we study the scattering of D 0 and D *0 mesons and their antiparticles off the X(3872) in an effective field theory for short-range interactions. We present results for the S-wave scattering amplitude, total interaction cross section and S-wave scattering length. (orig.)
Exotic nuclei: another aspect of nuclear structure
International Nuclear Information System (INIS)
Dobaczewski, J.; Blumenfeld, Y.; Flocard, H.; Garcia Borge, M.J.; Nowacki, F.; Rombouts, S.; Theisen, Ch.; Marques, F.M.; Lacroix, D.; Dessagne, P.; Gaeggeler, H.
2002-01-01
This document gathers the lectures made at the Joliot Curie international summer school in 2002 whose theme that year was exotic nuclei. There were 11 contributions whose titles are: 1) interactions, symmetry breaking and effective fields from quarks to nuclei; 2) status and perspectives for the study of exotic nuclei: experimental aspects; 3) the pairing interaction and the N = Z nuclei; 4) borders of stability region and exotic decays; 5) shell structure of nuclei: from stability to decay; 6) variational approach of system with a few nucleons; 7) from heavy to super-heavy nuclei; 8) halos, molecules and multi-neutrons; 9) macroscopic approaches for fusion reactions; 10) beta decay: a tool for spectroscopy; 11) the gas phase chemistry of super-heavy elements
Barriers in the energy of deformed nuclei
Directory of Open Access Journals (Sweden)
V. Yu. Denisov
2014-06-01
Full Text Available Interaction energy between two nuclei considering to their deformations is studied. Coulomb and nuclear in-teraction energies, as well as the deformation energies of both nuclei, are taken into account at evaluation of the interaction energy. It is shown that the barrier related to the interaction energy of two nuclei depends on the de-formations and the height of the minimal barrier is evaluated. It is obtained that the heavier nucleus-nucleus sys-tems have large deformation values at the lowest barrier. The difference between the barrier between spherical nuclei and the lowest barrier between deformed nuclei increases with the mass and the charge of the interacting nuclei.
Laser method of free atom nuclei orientation
International Nuclear Information System (INIS)
Barabanov, A.L.
1987-01-01
Orientation process of free atom (atoms in beams) nuclei, scattering quanta of circularly polarized laser radiation is considered. A method for the evaluation of nuclei orientation parameters is developed. It is shown that in the process of pumping between the ground and first excited atomic states with electron shell spins J 1 and J 2 , so that J 2 = J 1 + 1, a complete orientation of nuclei can be attained
Are there multiquark bags in nuclei
International Nuclear Information System (INIS)
Kondratyuk, L.A.; Scmatkov, M.Zh.
1983-01-01
Arguments are presented favouring the idea that multiquark bags do eXist in nuclei. Such hypothesis makes possible to reveal the relationship among three different scopes of phenomena: deep inelastic scattering of leptons by nUclei, large q 2 (where q 2 is a square of momentum transfer) behaviour of the form factors of light nuclei and yield of cumulative proton.s
Understanding Nuclei in the upper sd - shell
Sarkar, M. Saha; Bisoi, Abhijit; Ray, Sudatta; Kshetri, Ritesh; Sarkar, S.
2013-01-01
Nuclei in the upper-$sd$ shell usually exhibit characteristics of spherical single particle excitations. In the recent years, employment of sophisticated techniques of gamma spectroscopy has led to observation of high spin states of several nuclei near A$\\simeq$ 40. In a few of them multiparticle, multihole rotational states coexist with states of single particle nature. We have studied a few nuclei in this mass region experimentally, using various campaigns of the Indian National Gamma Array...
Possible existence of backbending in actinide nuclei
International Nuclear Information System (INIS)
Dudek, J.; Nazarewicz, W.; Szymanski, Z.
1982-01-01
The possibilities for the backbending effect to occur in actinide nuclei are studied using the pairing-self-consistent independent quasiparticle method. The Hamiltonian used is that of the deformed Woods-Saxon potential plus monopole pairing term. The results of the calculations explain why there is no backbending in most actinide nuclei and simultaneously suggest that in some light neutron deficient nuclei around Th and 22 Ra a backbending effect may occur
Nuclei quadrupole coupling constants in diatomic molecule
International Nuclear Information System (INIS)
Ivanov, A.I.; Rebane, T.K.
1993-01-01
An approximate relationship between the constants of quadrupole interaction of nuclei in a two-atom molecule is found. It enabled to establish proportionality of oscillatory-rotation corrections to these constants for both nuclei in the molecule. Similar results were obtained for the factors of electrical dipole-quadrupole screening of nuclei. Applicability of these relationships is proven by the example of lithium deuteride molecule. 4 refs., 1 tab
Nuclei at the limits of particle stability
International Nuclear Information System (INIS)
Mueller, A.C.
1993-01-01
The properties and synthesis of nuclei at the limits of particle stability are reviewed. Nuclear reactions were induced and studied by means of the 'exotic' nuclear beams, i.e. beams of radioactive drip-line nuclei. The beams are mostly generated in heavy-ion projectile fragmentation. The cases of both neutron-rich and proton-rich nuclei are discussed. (K.A.) 270 refs.; 13 figs.; 1 tab
Comparison of different proximity potentials for asymmetric colliding nuclei
International Nuclear Information System (INIS)
Dutt, Ishwar; Puri, Rajeev K.
2010-01-01
Using the different versions of phenomenological proximity potential as well as other parametrizations within the proximity concept, we perform a detailed comparative study of fusion barriers for asymmetric colliding nuclei with asymmetry parameter as high as 0.23. In all, 12 different proximity potentials are robust against the experimental data of 60 reactions. Our detailed study reveals that the surface energy coefficient as well as radius of the colliding nuclei depend significantly on the asymmetry parameter. All models are able to explain the fusion barrier heights within ±10% on the average. The potentials due to Bass 80, AW 95, and Denisov DP explain nicely the fusion cross sections at above- as well as below-barrier energies.
Problem of α-clustering levels in heavy nuclei
International Nuclear Information System (INIS)
Kadmenskij, V.G.; Kadmenskij, S.G.; Kurgalin, S.D.; Furman, V.I.
1982-01-01
From the optical model analysis of elastic scattering and absorption cross sections of α-particles including the (n,α) reaction induced by resonance neutrons it may be concluded that the conception of black nucleus is valid for α-particles. It was shown that the magnitudes of α-particle surface spectroscopic factors did not exceed 10sup(-2) for all the known α-transitions both in spherical and deformed heavy nuclei accounting for the ambiguities of the optical model potential. The possibilities of extracting the α-particles form factors of low-lying nuclear states from α-transfer reaction data are considered. From all the data considered it is concluded that there is no evidence for the revealing of α-clustering levels in heavy nuclei. (author)
Semimicroscopic description of the giant quadrupole resonances in deformed nuclei
International Nuclear Information System (INIS)
Kurchev, G.; Malov, L.A.; Nesterenko, V.O.; Soloviev, V.G.
1976-01-01
The calculation results of the giant quadrupole isoscalar and isovector resonances performed within the random phase approximation are represented. The strength functions for E2-transitions are calculated for doubly even deformed nuclei in the regions 150 (<=) A < 190 and 228 (<=) A < 248 in the energy interval (0-40) MeV. The following integral characteristics of giant quadrupole resonances are obtained: the position, widths, the contribution to the energy weighted sum rule and the contribution to the total cross section of photoabsorption. The calculations have shown that giant quadrupole resonances are common for all the considered nuclei. The calculated characteristics of the isoscalar giant quadrupole resonance agree with the available experimental data. The calculations also show that the semimicroscopic theory can be successfully applied for the description of giant multipole resonances
Scattering, diffraction and multiparticle production on hadron and nuclei at high energy
International Nuclear Information System (INIS)
Ter-Martirosyan, K.A.; Zoller, V.R.
1988-01-01
The cross sections for different types of interactions of hadronic with hadrons and nuclei at high energy are obtained in the simple form in the supercritical pomeron theory. Diffraction desintegration (DD) of hadrons both in the intermediate states, between rescatterings on pomerons, and in the final states is taken into account. With the same accuracy the cross sections δ n for production of n pomeron jets on hadrons and nuclei are also obtained. They determine the whole dynamics of the multiple particle productions, i.e. the spectra and multiplicities of produced particles, the cross sections for DD of colliding hadrons and nucleons inside the target nuclei. The numerical results for δ tot , δ el and for dδ el /dp tr 2 with the set of the pomeron and f, ω-reggeons pole parameters obtained early are presented. 19 refs.; 6 figs
Selfconsistent calculations for hyperdeformed nuclei
Energy Technology Data Exchange (ETDEWEB)
Molique, H.; Dobaczewski, J.; Dudek, J.; Luo, W.D. [Universite Louis Pasteur, Strasbourg (France)
1996-12-31
Properties of the hyperdeformed nuclei in the A {approximately} 170 mass range are re-examined using the self-consistent Hartree-Fock method with the SOP parametrization. A comparison with the previous predictions that were based on a non-selfconsistent approach is made. The existence of the {open_quotes}hyper-deformed shell closures{close_quotes} at the proton and neutron numbers Z=70 and N=100 and their very weak dependence on the rotational frequency is suggested; the corresponding single-particle energy gaps are predicted to play a role similar to that of the Z=66 and N=86 gaps in the super-deformed nuclei of the A {approximately} 150 mass range. Selfconsistent calculations suggest also that the A {approximately} 170 hyperdeformed structures have neglegible mass asymmetry in their shapes. Very importantly for the experimental studies, both the fission barriers and the {open_quotes}inner{close_quotes} barriers (that separate the hyperdeformed structures from those with smaller deformations) are predicted to be relatively high, up to the factor of {approximately}2 higher than the corresponding ones in the {sup 152}Dy superdeformed nucleus used as a reference.
Mass-23 nuclei in astrophysics
International Nuclear Information System (INIS)
Fraser, P R; Amos, K; Van der Kniff, D; Canton, L; Karataglidis, S; Svenne, J P
2015-01-01
The formation of mass-23 nuclei by radiative capture is of great interest in astrophysics. A topical problem associated with these isobars is the so-called 22 Na puzzle of ONe white dwarf novae, where the abundance of 22 Na observed is not as is predicted by current stellar models, indicating there is more to learn about how the distribution of elements in the universe occurred. Another concerns unexplained variations in elements abundance on the surface of aging red giant stars. One method for theoretically studying nuclear scattering is the Multi-Channel Algebraic Scattering (MCAS) formalism. Studies to date have used a simple collective-rotor prescription to model the target states which couple to projectile nucleons. While, in general, the target states considered all belong to the ground state rotor band, for some systems it is necessary to include coupling to states outside of this band. Herein we discuss an extension of MCAS to allow coupling of different strengths between such states and the ground state band. This consideration is essential when studying the scattering of neutrons from 22 Ne, a necessary step in studying the mass-23 nuclei mentioned above. (paper)
The Peculiarities of the Production and Decay of Superheavy Nuclei
International Nuclear Information System (INIS)
Itkis, M. G.; Bogachev, A. A.; Itkis, I. M.; Jandel, M.; Kliman, J.; Knyazheva, G. N.; Kondratiev, N. A.; Kozulin, E. M.; Krupa, L.; Oganessian, Yu. Ts.; Pokrovsky, I. V.; Prokhorova, E. V.; Rusanov, A. Ya.; Sagaidak, R. N.; Beghini, S.; Montagnoli, G.; Scarlassara, F.; Behera, B. R.; Corradi, L.; Fioretto, E.
2006-01-01
The interest in the study of the fission process of superheavy nuclei mainly deals with the opportunity to obtain information about the cross-section of the compound nucleus (CN) formation at excitation energies E*≅15-30 MeV. It allows one to estimate the survival probability of the superheavy composite system after evaporation of 1-3 neutrons, i.e. in 'cold' or 'warm' fusion reactions. However, in order to solve this problem deeper understanding of the coalescence processes between colliding nuclei, the competition between fusion-fission and quasi-fission processes is needed. The characteristics of both processes, their manifestation in the experimental observables and the relative contribution to the capture cross-section in dependence on the excitation energies, reaction entrance channel etc were investigated for a wide range of target-projectile combinations. Results of the experiments devoted to the study of the fusion-fission and quasi-fission processes in the reactions of the formation of the superheavy nuclei with Z = 102-122 are presented. The heavy ions 26Mg, 48Ca, 50Ti, 58Fe and 64Ni were used as projectiles. The choice of the reactions with 48Ca and actinide-targets was inspired by the experiments on the production of the isotopes 283112, 289114 and 283116 in Dubna using the same reactions. The 50Ti, 58Fe and 64Ni projectiles were chosen since the corresponding projectile-target combinations lead to the synthesis of even heavier elements. The experiments were carried out at the U-400 accelerator of the Flerov Laboratory of Nuclear Reactions (JINR, Russia) and the XTU Tandem accelerator of the National Laboratory of Legnaro (LNL, Italy) using the time-of-flight spectrometer of fission fragments CORSET. The role of the shell effects, the influence of the entrance channel asymmetry and the deformations of colliding nuclei on the mechanism of the fusion-fission and the competitive process of quasi-fission are discussed. The recent results on synthesis of
The asymptotic hadron spectrum, anti-nuclei, hyper-nuclei and quark phase
International Nuclear Information System (INIS)
Glendenning, N.K.
1978-01-01
The only hope of determining the hadronic spectrum in the high mass region is through a study of matter produced in very high energy nuclear collisions. Along the way, exotic nuclei, i.e., anti-nuclei and hyper-nuclei may be produced in appreciable numbers, and the detection of a quark phase may be possible. (orig.) [de
Gamow-Teller decay of T = 1 nuclei to odd-odd N = Z nuclei
Energy Technology Data Exchange (ETDEWEB)
Lisetskiy, A F [National Superconducting Cyclotron Laboratory, MSU, East Lansing, MI 48824 (United States); Gelberg, A [Institute for Nuclear Physics, University of Cologne, 50937 Cologne (Germany); Institute of Physical and Chemical Reasearch (RIKEN), Wako, 351-0198 (Japan); Brentano, P von [Institute for Nuclear Physics, University of Cologne, 50937 Cologne (Germany)
2005-01-01
Transition strengths of Gamow-Teller decay of T{sub z} = {+-}1 nuclei to N = Z odd-odd nuclei have been calculated in a two-nucleon approximation for spherical and deformed nuclei. The results obtained for the latter are quite close to the values obtained by full-space shell-model calculations and to the experiment.
Axial-Current Matrix Elements in Light Nuclei from Lattice QCD
Energy Technology Data Exchange (ETDEWEB)
Savage, Martin [Univ. of Washington, Seattle, WA (United States); Shanahan, Phiala E. [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Tiburzi, Brian C. [Univ. of Maryland, College Park, MD (United States); Wagman, Michael L. [Univ. of Washington, Seattle, WA (United States); Winter, Frank T. [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Beane, Silas [Univ. of New Hampshire, Durham, NH (United States); Chang, Emmanuel [Univ. of Washington, Seattle, WA (United States); Davoudi, Zohreh; Detmold, William [Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States); Orginos, Konstantinos [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); College of William and Mary, Williamsburg, VA (United States)
2016-12-01
I present results from the first lattice QCD calculations of axial-current matrix elements in light nuclei, performed by the NPLQCD collaboration. Precision calculations of these matrix elements, and the subsequent extraction of multi-nucleon axial-current operators, are essential in refining theoretical predictions of the proton-proton fusion cross section, neutrino-nucleus cross sections and $\\beta\\beta$-decay rates of nuclei. In addition, they are expected to shed light on the phenomenological quenching of $g_A$ that is required in nuclear many-body calculations.
Short Range Correlations in Nuclei at Large xbj through Inclusive Quasi-Elastic Electron Scattering
Energy Technology Data Exchange (ETDEWEB)
Ye, Zhihong [Univ. of Virginia, Charlottesville, VA (United States)
2013-12-01
The experiment, E08-014, in Hall-A at Jefferson Lab aims to study the short-range correlations (SRC) which are necessary to explain the nuclear strength absent in the mean field theory. The cross sections for 2H, 3He, 4He, 12C, 40Ca and 48Ca, were measured via inclusive quasi-elastic electron scattering from these nuclei in a Q2 range between 0.8 and 2.8 (GeV/c)^{2} for x>1. The cross section ratios of heavy nuclei to 2H were extracted to study two-nucleon SRC for 1
Reaction Mechanism and Structure Interplay for Proton Elastic Scattering from Halo Nuclei
International Nuclear Information System (INIS)
Crespo, R.; Johnson, R.C.
1999-01-01
The aim of this work is to clarify what properties of the projectile w.f. are relevant to describe elastic scattering of halo nuclei from stable nuclei. In particular, we examine how far elastic scattering observables probe correlation effects among projectile nucleons. Our treatment is based on a multiple scattering expansion of the proton-projectile transition amplitude in a form which is well adapted to the weakly bound cluster picture of halo nuclei. In the specific case of 11 Li scattering from protons at 800 MeV/u we show that because core recoil effects are significant, scattering cross sections can not, in general, be deduced from knowledge of the total matter density alone. We advocate that the optical potential concept for the scattering of halo nuclei on protons should be avoided and that the multiple scattering series for the full transition amplitude should be used instead
Photodisintegration of Light Nuclei with CLAS
Energy Technology Data Exchange (ETDEWEB)
Ilieva, Yordanka Yordanova [University of South Carolina; Zachariou, Nicholas [University of South Carolina
2013-08-01
We report preliminary results of photodisintegration of deuteron and {sup 3}He measured with CLAS at Jefferson Lab. We have extracted the beam-spin asymmetry for the {vector {gamma}}d {yields} pn reaction at photon energies from 1.1 GeV to 2.3 GeV and proton center-of-mass (c.m.) angles between 35{degrees} and 135{degrees} . Our data show interesting evolution of the angular dependence of the observable as the photon energy increases. The energy dependence of the beam-spin asymmetry at 90 shows a change of slope at photon energy of 1.6 GeV. A comparison of our data with model calculations suggests that a fully non-perturbative treatment of the underlying dynamics may be able to describe the data better than a model based on hard scattering. We have observed onset of dimensional scaling in the cross section of two-body photodisintegration of {sup 3}He at remarkably low energy and momentum transfer, which suggests that partonic degrees of freedom may be relevant for the description of nuclei at energies lower than previously considered.
Heavy quarkonium production and propagation in nuclei
International Nuclear Information System (INIS)
Wong, C.Y.
1997-01-01
In the search for the quark-gluon plasma, it has been suggested that the production of charmonium will be suppressed in a quark-gluon plasma because of the screening of the interaction between c and anti c. To extract information on the suppression due to the quark-gluon plasma, it is necessary to study the suppression of J/ψ production by sources different from the quark-gluon plasma. It is therefore useful to examine the mechanism of heavy quarkonium production and its propagation in nuclei. The authors describe a precursor in heavy quarkonium production in terms of a coherent admixture of states of different color, spin, and angular momentum quantum numbers, and obtain the production amplitudes for different quarkonium bound states by projecting out this precursor state onto these bound states. The precursor is absorbed in its passage through a nucleus in a pA reaction, and the total cross section between this precursor with a nucleon can be calculated with the two-gluon model of the Pomeron. Such a description of coherent precursors and their subsequent interactions with nucleons can explain many salient features of J/ψ and ψ' production in pA collisions
Composite hadrons and relativistic nuclei
International Nuclear Information System (INIS)
Blankenbecler, R.
1978-01-01
Lectures are presented describing a model of hadronic scattering at large momentum transfer, either transverse or longitudinal. This model emphasizes in this regime the importance of forces involving the interchange of constituents of the hadrons, hence its name, the constituent interchange model CIM. The CIM is a rearrangement of standard perturbation theory to take into account the fact that the binding force is very strong in color singlet states (singlet dominance). The hard scattering expansion, incoherence problems, nuclear wave functions and counting rules, interaction between nuclei, pion and proton yields and form factors, structure functions and nonscaling, massive lepton pairs, hadrons at large transverse momentum, and quark-quark scattering are treated. 49 references
Neutron halo in deformed nuclei
International Nuclear Information System (INIS)
Zhou Shangui; Meng Jie; Ring, P.; Zhao Enguang
2010-01-01
Halo phenomena in deformed nuclei are investigated within a deformed relativistic Hartree Bogoliubov (DRHB) theory. These weakly bound quantum systems present interesting examples for the study of the interdependence between the deformation of the core and the particles in the halo. Contributions of the halo, deformation effects, and large spatial extensions of these systems are described in a fully self-consistent way by the DRHB equations in a spherical Woods-Saxon basis with the proper asymptotic behavior at a large distance from the nuclear center. Magnesium and neon isotopes are studied and detailed results are presented for the deformed neutron-rich and weakly bound nucleus 44 Mg. The core of this nucleus is prolate, but the halo has a slightly oblate shape. This indicates a decoupling of the halo orbitals from the deformation of the core. The generic conditions for the occurrence of this decoupling effects are discussed.
International Nuclear Information System (INIS)
Soloviev, V.G.
1995-01-01
Order and chaos and order-to-chaos transition are treated in terms of nuclear wave functions. A quasiparticle-phonon interaction is responsible for the fragmentation of one- and many-quasiparticle and phonon states and for the mixing of closely spaced states. Complete damping of one-quasiparticle states cannot be considered as a transition to chaos due to large many-quasiparticle or quasiparticle-phonon terms in their wave functions. An experimental investigation of the strength distribution of many-quasiparticle and quasiparticle-phonon states should uncover a new region of a regularity in nuclei at intermediate excitation energy. A chaotic behaviour of nuclear states can be shifted to higher excitation energies. ((orig.))
Relativistic description of atomic nuclei
International Nuclear Information System (INIS)
Krutov, V.A.
1985-01-01
Papers on the relativistic description of nuclei are reviewed. The Brown and Rho ''small'' bag'' model is accepted for hardrons. Meson exchange potentials of the nucleon-nucleon interaction have been considered. Then the transition from a system of two interacting nucleons has been performed to the relativistic nucleus description as a multinucleon system on the basis of OBEP (one-boson exchange potential). The proboem of OPEP (one-pion-exchange potential) inclusion to a relativistic scheme is discussed. Simplicity of calculations and attractiveness of the Walecka model for specific computations and calculations was noted. The relativistic model of nucleons interacting through ''effective'' scalar and vector boson fields was used in the Walacka model for describing neutronaand nuclear mater matters
Electric quadrupole strength in nuclei
International Nuclear Information System (INIS)
Kirson, M.W.
1979-01-01
Isoscalar electric quadrupole strength distributions in nuclei are surveyed, and it is concluded that the strength is shared, in most cases, roughly equally between low-lying transitions and the giant quadrupole state. The same is not true of the isovector case. A simple extension of the schematic model gives a remarkably successul description of the data, and emphasizes the vital importance of the coupling between high-lying and low-lying quadrupole modes. The standadrd simple representation of the giant quadrupole resonance as produced by operating on the nuclear ground state with the quadrupole transition operator is not applicable to the isoscalar case. It is suggested that giant resonances fall into broad classes of similar states, with considerable qualitative differences between the distinct classes. (author)
Cavitation Nuclei: Experiments and Theory
DEFF Research Database (Denmark)
Mørch, Knud Aage
2009-01-01
The Swedish astrophysicist and Nobel Prize winner Hannes Alfven said: Theories come and go - the experiment is here forever. Often a theory, which we set up to describe an observed physical phenomenon, suffers from the lack of knowledge of decisive parameters, and therefore at best the theory...... becomes insufficient. Contrary, the experiment always reveals nature itself, though at prevailing experimental conditions. With essential parameters being out of control and even maybe unidentified, apparently similar experiments may deviate way beyond our expectations. However, these discrepancies offer...... us a chance to reflect on the character of the unknown parameters. In this way non-concordant experimental results may hold the key to the development of better theories - and to new experiments for the testing of their validity. Cavitation and cavitation nuclei are phenomena of that character....
Femtometer toroidal structures in nuclei
International Nuclear Information System (INIS)
Forest, J.L.; Pandharipande, V.R.; Pieper, S.C.; Wiringa, R.B.; Schiavilla, R.; Arriaga, A.
1996-01-01
The two-nucleon density distributions in states with isospin T=0, spin S=1, and projection M S =0 and ±1 are studied in 2 H, 3,4 He, 6,7 Li, and 16 O. The equidensity surfaces for M S =0 distributions are found to be toroidal in shape, while those of M S =±1 have dumbbell shapes at large density. The dumbbell shapes are generated by rotating tori. The toroidal shapes indicate that the tensor correlations have near maximal strength at r 3 He, 4 He, and 6 Li. The toroidal distribution has a maximum-density diameter of ∼1 fm and a half-maximum density thickness of ∼0.9 fm. Many realistic models of nuclear forces predict these values, which are supported by the observed electromagnetic form factors of the deuteron, and also predicted by classical Skyrme effective Lagrangians, related to QCD in the limit of infinite colors. Due to the rather small size of this structure, it could have a revealing relation to certain aspects of QCD. Experiments to probe this structure and its effects in nuclei are suggested. Pair distribution functions in other T,S channels are also discussed; those in T,S=1,1 have anisotropies expected from one-pion-exchange interactions. The tensor correlations in T,S=0,1 states are found to deplete the number of T,S=1,0 pairs in nuclei and cause a reduction in nuclear binding energies via many-body effects. copyright 1996 The American Physical Society
International Nuclear Information System (INIS)
Rho, M.
1981-01-01
Quantum chromodynamics is believed to be candidate theory for the strong interactions and contains as its ingredients spinor quark fields and vector gluons, none of which can perhaps be ever liberated and detected in laboratories. A nucleus consists of nucleons bound by nuclear force which are however separately observable and which seem to preserve their identities even under extreme conditions. An intriguing question is: when compressed to high densities or heated to high temperature, at what point does a nuclear matter cease to be describable in terms of nucleon and meson degrees of freedom, but become a plasma of quarks and gluons; and how does this transition occur. This is not an idle question. If quarks and gluons are never to be observed isolated, then it may be that at low energies (or at low densities) they are not the right variables to do physics with. Instead hadrons must be. On the other hand, asymptotic freedom - the unique property of non-abelian gauge theories to which QCD belongs that quark-gluon and gluon-gluon interactions get weaker at short distances - tells us that at some large matter density the matter must necessarily be in the form of quark gas interacting only weakly. This means that a change in degrees of freedom must take place. We would like to know where this occurs and how. In this talk, I would like to address to this question by discussing first the large success we have had in understanding the role that mesons play in finite nuclei and nuclear matter and then attempting to correlate nucleon and meson degrees of freedom to quark-gluon degrees of freedom. In my opinion we are now at a stage where we feel fairly confident in our understanding of nucleon-meson structure of nuclei and nuclear matter and any further progress in deeper understanding of nuclear dynamics - and strong interactions - must come from QCD or its effective version, bags or strings. (orig.)
Mean-field models and exotic nuclei
Energy Technology Data Exchange (ETDEWEB)
Bender, M; Buervenich, T; Maruhn, J A; Greiner, W [Inst. fuer Theoretische Physik, Univ. Frankfurt (Germany); Rutz, K [Inst. fuer Theoretische Physik, Univ. Frankfurt (Germany); [Gesellschaft fuer Schwerionenforschung mbH, Darmstadt (Germany); Reinhard, P G [Inst. fuer Theoretische Physik, Univ. Erlangen (Germany)
1998-06-01
We discuss two widely used nuclear mean-field models, the relativistic mean-field model and the (nonrelativistic) Skyrme-Hartree-Fock model, and their capability to describe exotic nuclei. Test cases are superheavy nuclei and neutron-rich Sn isotopes. New information in this regime helps to fix hitherto loosely determined aspects of the models. (orig.)
High-spin excitations of atomic nuclei
International Nuclear Information System (INIS)
Xu Furong; National Laboratory of Heavy Ion Physics, Lanzhou; Chinese Academy of Sciences, Beijing
2004-01-01
The authors used the cranking shell model to investigate the high-spin motions and structures of atomic nuclei. The authors focus the collective rotations of the A∼50, 80 and 110 nuclei. The A∼50 calculations show complicated g spectroscopy, which can have significant vibration effects. The A≅80 N≅Z nuclei show rich shape coexistence with prolate and oblate rotational bands. The A≅110 nuclei near the r-process path can have well-deformed oblate shapes that become yrast and more stable with increasing rotational frequency. As another important investigation, the authors used the configuration-constrained adiabatic method to calculate the multi-quasiparticle high-K states in the A∼130, 180 and superheavy regions. The calculations show significant shape polarizations due to quasi-particle excitations for soft nuclei, which should be considered in the investigations of high-K states. The authors predicted some important high-K isomers, e.g., the 8 - isomers in the unstable nuclei of 140 Dy and 188 Pb, which have been confirmed in experiments. In superheavy nuclei, our calculations show systematic existence of high-K states. The high-K excitations can increase the productions of synthesis and the survival probabilities of superheavy nuclei. (authors)
Microscopic Cluster Theory for Exotic Nuclei
International Nuclear Information System (INIS)
Tomaselli, M; Kuehl, T; Ursescu, D; Fritzsche, S
2006-01-01
For a better understanding of the dynamics of complex exotic nuclei it is of crucial importance to develop a practical microscopic theory easy to be applied to a wide range of masses. In this paper we propose to calculate the structure of neutron-rich nuclei within a dynamic model based on the EoM theory
Reentrainment of radioactive nuclei from filters
International Nuclear Information System (INIS)
Dincklage, R.-D. von
1982-01-01
The possible relevance of atomic phenomena for the reentrainment of radioactive nuclei is discussed. The considerations are based on the coulombic fragmentation mechanism. Nuclei of potential interest in reprocessing technology are identified. Future experiments have been shown to be of definite need in this field. (author)
Thermodynamics of pairing phase transition in nuclei
International Nuclear Information System (INIS)
Karim, Afaque; Ahmad, Shakeb
2014-01-01
The pairing gaps, pairing energy, heat capacity and entropy are calculated within BCS (Bardeen- Cooper-Schrieffer) based quasi particle approach, including thermal fluctuations on pairing field within pairing model for all nuclei (light, medium, heavy and super heavy nuclei). Quasi particles approach in BCS theory was introduced and reformulated to study various properties. For thermodynamic behavior of nuclei at finite temperatures, the anomalous averages of creation and annihilation operators are introduced. It is solved self consistently at finite temperatures to obtain BCS Hamiltonian. After doing unitary transformation, we obtained the Hamiltonian in the diagonal form. Thus, one gets temperature dependence gap parameter and pairing energy for nuclei. Moreover, the energy at finite temperatures is the sum of the condensation energy and the thermal energy of fermionic quasi particles. With the help of BCS Hamiltonian, specific heat, entropy and free energy are calculated for different nuclei. In this paper the gap parameter occupation number and pairing energy as a function of temperature which is important for all the light, medium, heavy and super heavy nuclei is calculated. Moreover, the various thermo dynamical quantities like specific heat, entropy and free energy is also obtained for different nuclei. Thus, the thermodynamics of pairing phase transition in nuclei is studied
Mean-field models and exotic nuclei
International Nuclear Information System (INIS)
Bender, M.; Buervenich, T.; Maruhn, J.A.; Greiner, W.; Rutz, K.; Reinhard, P.G.
1998-01-01
We discuss two widely used nuclear mean-field models, the relativistic mean-field model and the (nonrelativistic) Skyrme-Hartree-Fock model, and their capability to describe exotic nuclei. Test cases are superheavy nuclei and neutron-rich Sn isotopes. New information in this regime helps to fix hitherto loosely determined aspects of the models. (orig.)
Static and dynamical properties of hot nuclei
International Nuclear Information System (INIS)
Suraud, E.
1990-01-01
We briefly review our understanding of the formation of excited/hot nuclei in heavy-ion collisions at some tens of MeV/A. We recall the major theoretical frameworks used for describing as well the entrance channel of the reaction as the structure properties of hot nuclei. We finally focus on multifragmentation within insisting upon the theoretical challenge it does represent
Masses of nuclei close to the dripline
International Nuclear Information System (INIS)
Herfurth, F.; Blaum, K.; Audi, G.; Lunney, D.; Beck, D.; Kluge, H.J.; Rodriguez, D.; Sikler, G.; Weber, C.; Bollen, G.; Schwarz, S.; Kellerbauer, A.
2003-01-01
Mass measurements of radioactive nuclides are one of the cornerstones of our understanding of the nucleus. The Penning trap spectrometer ISOLTRAP performs direct mass measurements far away from the valley of stability, as well as high-precision measurements of key nuclei to anchor long decay chains. Both schemes provide valuable information on the dripline itself and on nuclei in its close vicinity. (orig.)
Quasars, Seyfert galaxies and active galactic nuclei
International Nuclear Information System (INIS)
Osterbrock, D.E.
1987-01-01
This chapter is devoted to the spectroscopic methods for analyzing the observed plasma in the nuclei of quasars, Seyfert galazies, and active galactic nuclei. Both the narrow-line region and the broad-line region are discussed. Physical models are presented
Single Particle Entropy in Heated Nuclei
International Nuclear Information System (INIS)
Guttormsen, M.; Chankova, R.; Hjorth-Jensen, M.; Rekstad, J.; Siem, S.; Sunde, A. C.; Syed, N. U. H.; Agvaanluvsan, U.; Schiller, A.; Voinov, A.
2006-01-01
The thermal motion of single particles represents the largest contribution to level density (or entropy) in atomic nuclei. The concept of single particle entropy is presented and shown to be an approximate extensive (additive) quantity for mid-shell nuclei. A few applications of single particle entropy are demonstrated
Quantum phase transitions in atomic nuclei
International Nuclear Information System (INIS)
Zamfir, N.V.
2005-01-01
Studies of quantum phase transitions in mesoscopic systems and applications to atomic nuclei are presented. Analysis in terms of the Interacting Boson Model shows that the main features persist even for moderate number of particles. Experimental evidence in rare-earth nuclei is discussed. New order and control parameters for systems with the same number of particles are proposed. (author)
Structure and clusters of light unstable nuclei
International Nuclear Information System (INIS)
En'yo, Yoshiko
2010-01-01
As it is known, cluster structures are often observed in light nuclei. In the recent evolution of unstable nuclear research (on nuclei having unbalanced number of neutron and proton) further new types of clusters are coming to be revealed. In this report, structures of light unstable nuclei and some of the theoretical models to describe them are reviewed. The following topics are picked up. 1. Cluster structure and theoretical models, 2. Cluster structure of unstable nuclei (low excited state). 3. Cluster structure of neutron excess beryllium isotopes. 4. Cluster gas like state in C isotope. 5. Dineutron structure of He isotopes. Numbers of strange nuclear structures of light nuclei are illustrated. Antisymmetrized molecular dynamics (AMD) is the recently developed theoretical framework which has been successfully used in heavy ion reactions and nuclear structure studies. Successful application of AMD to the isotopes of Be, B and C are illustrated. (S. Funahashi)
Structure of Light Neutron-rich Nuclei
International Nuclear Information System (INIS)
Dlouhy, Zdenek
2007-01-01
In this contribution we searched for irregularities in various separation energies in the frame of mass measurement of neutron-rich nuclei at GANIL. On this basis we can summarize that the new doubly magic nuclei are 8 He, 22 O and 24 O. They are characterized by extra stability and, except 24 O, they cannot accept and bind additional neutrons. However, if we add to these nuclei a proton we obtain 9 Li and 25 F which are the core for two-neutron halo nucleus 11 Li and enables that fluorine can bound even 6 more neutrons, respectively. In that aspect the doubly magic nuclei in the neutron-rich region can form the basis either for neutron halo or very neutron-rich nuclei. (Author)
Strength of Coriolis Coupling in actinide nuclei
International Nuclear Information System (INIS)
Peker, L.K.; Rasmussen, J.O.; Hamilton, J.H.
1982-01-01
Coriolis Coupling V/sub cor/ plays an important role in deformed nuclei. V/sub cor/ is proportional to h 2 /J[j (j + 1) -Ω (Ω + 1)]/sup 1/2/ and therefore is particularly significant in the nuclei with large j and low Ω Nilsson levels close to Fermi surface: n(i/sub 13/2/) in A = 150 to 170 rare-earth nuclei and p(i/sub 13/2/) and n(j/sub 15/2/) in A greater than or equal to 224 actinide nuclei. Because of larger j (n(j/sub 15/2/) versus n(i/sub 13/2/)) and smaller deformations (β approx. = 0.22 versus β 0.28) it was reasonable to expect that in actinide nuclei Coriolis effects are stronger than in the rare earth nuclei. Recently it was realized that the strength of observed Coriolis effects depends not only on the genuine Coriolis Coupling but also on the interplay between Coriolis ad pairing forces which leads to an interference between the wave functions of two mixing rotational bands. As a consequence the effective interaction V/sub eff/ of both bands is an oscillating function of the degree of shell filling (or chemical potential lambda F). It was shown that in the rare earth nuclei this interference strongly influenced conclusions about the trends in the Coriolis coupling strength and explained many of the observed band-mixing features (the sharpness of back banding curves, details of the blocking effect etc.). From theoretical analysis it was concluded that in the majority of actinide nuclei the effective interaction V/sub eff/ is strong, and therefore the Coriolis band-mixing have to be very strong. In this paper we would like to demonstrate that contrary to these predictions experimental data suggest that Coriolis band mixing in studied actinide nuclei is relatively weak and possibly significantly weaker than in rare earth nuclei
Pion-nucleus cross sections approximation
International Nuclear Information System (INIS)
Barashenkov, V.S.; Polanski, A.; Sosnin, A.N.
1990-01-01
Analytical approximation of pion-nucleus elastic and inelastic interaction cross-section is suggested, with could be applied in the energy range exceeding several dozens of MeV for nuclei heavier than beryllium. 3 refs.; 4 tabs
International Nuclear Information System (INIS)
Volkov, V.V.
1980-01-01
Some experimental data are considered that indicate the validity of the Q/sub gg/ systematics of cross sections for production of isotopes in multinucleon transfer reactions for any target-projectile combination. The effect of the nuclear structure of the light fragment on the evolution and disintegration of the double nuclear system formed in deep inelastic collisions of complex nuclei is discussed. Predominance of the α-particle emission over all other channels of the disintegration of the double nuclear system is demonstrated. It is shown that deep inelastic transfer reactions can be used to study the deformation of nuclei with large angular momenta. 9 figures
Quantum effects and colour transparency in charmonium photoproduction on nuclei
International Nuclear Information System (INIS)
Kopeliovich, B.Z.; Zakharov, B.G.
1991-01-01
A rigorous quantum-mechanical treatment of colour transparency effects in diffractive photoproduction of c-barc-pairs on nuclei was developed. The evolution of the c-barc wave function during propagating through a nucleus is rather a considerable distortion of its form, than a trivial attenuation. One of the manifestations of the quantum effects is a nuclear antishadowing of Ψ' yield, i.e. transparency above one. On the contrary, a considerable nuclear shadowing is predicted for the photoproduction of J/Ψ, which has a much smaller absorption cross section than Ψ'. 26 refs.; 5 figs.; 1 tab
Heavy ion collisions and quark distribution in nuclei
International Nuclear Information System (INIS)
Liu Lian-sou; Pan Ji-cai; Peng Hung-an
1986-01-01
Heavy-ion collisions are studied by means of two-component Fokker--Planck equations on the assumption that there exist multiquark states in nuclei. Inclusive cross sections for the production of protons are calculated in heavy-ion collisions of C+C, Ne+NaF, and Ar+KCl at 800 MeV/A; Ne+Na at 400 MeV/A, 800 MeV/A, and 2100 MeV/A. Satisfactory agreement with the experimental data near 90 degrees c.m. is obtained. The production of deuterons in the collision of C+C at 800 MeV/A is also discussed
Scattering of polarized protons by yttrium, iron and nickel nuclei
International Nuclear Information System (INIS)
Melssen, J.P.M.G.
1978-01-01
Results are presented of scattering experiments performed on yttrium and some iron and nickel isotopes with polarized proton beams at energies around 20 MeV. The angular distributions of the differential cross sections and analyzing powers have been measured and comparison of these with predictions from theoretical models has led to information about excited nuclear states like spin, parity and details of the wavefunctions. The DWBA has been mostly used to describe the reaction at the bombarding energies and for the target nuclei investigated. (C.F.)
Proton-gamma coincidence experiment on medium mass nuclei at 400MeV and study of reaction mechanisms
International Nuclear Information System (INIS)
Baldit, Alain.
1981-01-01
Previous γ ray production experiments produced by proton on nuclei show important cross sections for residual nuclei corresponding to a four nucleon (2p + 2n) removal. With our (p - γ) coincidence experiment the forward emitted proton reflects the primary interaction and the γ spectra characterizes the final state of the reaction. Protons are detected with a magnetic spectrometer and γ rays are selected with a Ge(Li) diode. Angular and momentum analysis of scattered protons demonstrate a primary quasi free process on nucleons. No indication of knock out reactions on clusters has been seen. The residual nuclei are mainly produced by evaporation processes. A theoretical calculation involving intranuclear cascades and evaporation processes has been performed. The nucleus model is based upon a Fermi gas and nuclear density agrees with diffusion electron experiments. Residual nuclei far from target are well described with a such model. Residual nuclei near the target are sensitive to the nuclear structure [fr
2017-01-01
This note complements the paper titled: ``Production of deuterons, tritons, $^{3}$He nuclei and their anti-nuclei in pp collisions at $\\sqrt{s}$~=~0.9, 2.76 and 7~TeV'' with additional material related to Monte Carlo simulations necessary to compare the results with lower energy experiments. It describes a coalescence-based afterburner for QCD-inspired event generators, which allows the generation of light nuclei, hyper-nuclei and their charge conjugates in proton--proton (pp) collisions at LHC energies. The event generators with the afterburner are able to reproduce the differential cross sections of light (anti-)nuclei ($A<4)$ with the same degree of agreement as those of protons and anti-protons at the same momentum per nucleon. They also explain the transverse momentum dependence of the coalescence parameters as the result of hard scattering effects.
Hybrid theory and calculation of e-N2 scattering. [quantum mechanics - nuclei (nuclear physics)
Chandra, N.; Temkin, A.
1975-01-01
A theory of electron-molecule scattering was developed which was a synthesis of close coupling and adiabatic-nuclei theories. The theory is shown to be a close coupling theory with respect to vibrational degrees of freedom but is a adiabatic-nuclei theory with respect to rotation. It can be applied to any number of partial waves required, and the remaining ones can be calculated purely in one or the other approximation. A theoretical criterion based on fixed-nuclei calculations and not on experiment can be given as to which partial waves and energy domains require the various approximations. The theory allows all cross sections (i.e., pure rotational, vibrational, simultaneous vibration-rotation, differential and total) to be calculated. Explicit formulae for all the cross sections are presented.
RADIO VARIABILITY IN SEYFERT NUCLEI
International Nuclear Information System (INIS)
Mundell, C. G.; Ferruit, P.; Nagar, N.; Wilson, A. S.
2009-01-01
Comparison of 8.4 GHz radio images of a sample of eleven, early-type Seyfert galaxies with previous observations reveals possible variation in the nuclear radio flux density in five of them over a seven year period. Four Seyferts (NGC 2110, NGC 3081, MCG -6-30-15, and NGC 5273) show a decline in their 8.4 GHz nuclear flux density between 1992 and 1999, while one (NGC 4117) shows an increase; the flux densities of the remaining six Seyferts (Mrk 607, NGC 1386, Mrk 620, NGC 3516, NGC 4968, and NGC 7465) have remained constant over this period. New images of MCG -5-23-16 are also presented. We find no correlation between radio variability and nuclear radio luminosity or Seyfert nuclear type, although the sample is small and dominated by type 2 Seyferts. Instead, a possible correlation between the presence of nuclear radio variability and the absence of hundred parsec-scale radio emission is seen, with four out of five marginally resolved or unresolved nuclei showing a change in nuclear flux density, while five out of six extended sources show no nuclear variability despite having unresolved nuclear sources. NGC 2110 is the only source in our sample with significant extended radio structure and strong nuclear variability (∼38% decline in nuclear flux density over seven years). The observed nuclear flux variability indicates significant changes are likely to have occurred in the structure of the nucleus on scales smaller than the VLA beam size (i.e., within the central ∼0.''1 (15 pc)), between the two epochs, possibly due to the appearance and fading of new components or shocks in the jet, consistent with previous detection of subparsec-scale nuclear structure in this Seyfert. Our results suggest that all Seyferts may exhibit variation in their nuclear radio flux density at 8.4 GHz, but that variability is more easily recognized in compact sources in which emission from the variable nucleus is not diluted by unresolved, constant flux density radio jet emission
Production of actinide nuclei by multi-nucleon transfer
Energy Technology Data Exchange (ETDEWEB)
Lauritsen, T.; Ahmad, I.; Carpenter, M.P. [and others
1995-08-01
Multi-nucleon transfers have increasingly allowed us to reach parts of the nuclear chart where regular compound nuclear reactions are prohibited. The interesting region of Ra and Rn, where a rich tapestry of nuclear structure manifests itself, is now accessible using this technique of deep inelastic scattering. In particular, these nuclei are predicted to lie at the onset of octupole deformation and the region is rich in examples of shape coexistence. There are several theoretical predictions of nuclear structure of these nuclei that have not been experimentally tested. Moreover, there is serious disagreement among these theories. We used a beam of {sup 136}Xe at 720 MeV from ATLAS on a target of {sup 232}Th to produce a range of Rn isotopes, with a mass from 220 to 224, and Ra isotopes with masses greater than 222. The beam energy, target and beam were selected carefully to enhance the cross-section for production of these nuclei and reduce the Doppler broadening of the gamma rays that were observed in the Argonne Notre Dame gamma-ray facility. The 12 germanium detectors of this array allowed the observation of gamma-gamma coincidences. The inner ball of 50 BGO detectors allowed us to record the multiplicity and sum-energy information for each event. The latter should permit us to determine the entry region in the products of the transfer reaction. We had four successful days of beam-time, when we collected in excess of 8 x 10{sup 7} events. Data analysis is in progress at the University of Liverpool. A complete set of spectroscopic information on the yrast structure of the many nuclei produced in this reaction is being extracted.
On the unified system of the nucleons in nuclei
International Nuclear Information System (INIS)
Sharafiddinov, R.S.
2005-01-01
Full text: One of an innate features of the interaction of neutrons and protons in nuclei is the connection between these phenomena and character of the structure of nucleons themselves. At the same time a question about the appearance of the united system of massive fermions of the different nature requires the special investigation. Our study of the behavior of massive Dirac neutrinos in a nucleus field shows clearly that the mass and charge of a particle correspond to two form of the unified regularity of the ultimate structure of this field. Thereby such a mass - charge duality of matter explains the coexistence of the united force, mass and charge. In the present work, we discuss the problem of the unified system of the structural particles in nuclei investigating the most diverse symmetries of Dirac fermions at the interaction of massive neutrinos with nuclei of electroweak charges. It is assumed that the neutrino has the longitudinal as well as the transversal polarization. In this connection appears of principle possibility to directly look at the nature of an incoming lepton and the united system of hadrons themselves. With the use of the studied processes cross sections a proof has been obtained regardless of a particle type, the appearance of the connected system of massive fermions can be explained by the interference of their currents of the different symmetrically. Findings allow to establish at the fundamental level the compound structure of the interaction of nucleons in nuclei elucidating the inter-ratio of intranuclear forces and the nature of invariance of these types of the actions concerning C, P and T, and also their combinations CP and CPT which open up new possibilities for solution of the problem of elementary particle chiral and isotopic symmetries
International Nuclear Information System (INIS)
Clark, R.; Wadsworth, B.
1998-01-01
Magnetic rotation is a new phenomenon that is forcing physicists to rethink their understanding of what goes on inside the nucleus The rotation of quantum objects has a long and distinguished history in physics. In 1912 the Danish scientist Niels Bjerrum was the first to recognize that the rotation of molecules is quantized. In 1938 Edward Teller and John Wheeler observed similar features in the spectra of excited nuclei, and suggested that this was caused by the nucleus rotating. But a more complete explanation had to wait until 1951, when Aage Bohr (the son of Niels) pointed out that rotation was a consequence of the nucleus deforming from its spherical shape. We owe much of our current understanding of nuclear rotation to the work of Bohr and Ben Mottelson, who shared the 1975 Nobel Prize for Physics with James Rainwater for developing a model of the nucleus that combined the individual and collective motions of the neutrons and protons inside the nucleus. What makes it possible for a nucleus to rotate? Quantum mechanically, a perfect sphere cannot rotate because it appears the same when viewed from any direction and there is no point of reference against which its change in position can be detected. To see the rotation the spherical symmetry must be broken to allow an orientation in space to be defined. For example, a diatomic molecule, which has a dumbbell shape, can rotate about the two axes perpendicular to its axis of symmetry. A quantum mechanical treatment of a diatomic molecule leads to a very simple relationship between rotational energy, E, and angular momentum. This energy is found to be proportional to J(J + 1), where J is the angular momentum quantum number. The molecule also has a magnetic moment that is proportional to J. These concepts can be applied to the atomic nucleus. If the distribution of mass and/or charge inside the nucleus becomes non-spherical then the nucleus will be able to rotate. The rotation is termed ''collective'' because many
Symmetry and Phase Transitions in Nuclei
International Nuclear Information System (INIS)
Iachello, F.
2009-01-01
Phase transitions in nuclei have received considerable attention in recent years, especially after the discovery that, contrary to expectations, systems at the critical point of a phase transition display a simple structure. In this talk, quantum phase transitions (QPT), i.e. phase transitions that occur as a function of a coupling constant that appears in the quantum Hamiltonian, H, describing the system, will be reviewed and experimental evidence for their occurrence in nuclei will be presented. The phase transitions discussed in the talk will be shape phase transitions. Different shapes have different symmetries, classified by the dynamic symmetries of the Interacting Boson Model, U(5), SU(3) and SO(6). Very recently, the concept of Quantum Phase Transitions has been extended to Excited State Quantum Phase Transitions (ESQPT). This extension will be discussed and some evidence for incipient ESQPT in nuclei will be presented. Systems at the critical point of a phase transition are called 'critical systems'. Approximate analytic formulas for energy spectra and other properties of 'critical nuclei', in particular for nuclei at the critical point of the second order U(5)-SO(6) transition, called E(5), and along the line of first order U(5)-SU(3) transitions, called X(5), will be presented. Experimental evidence for 'critical nuclei' will be also shown. Finally, the microscopic derivation of shape phase transitions in nuclei within the framework of density functional methods will be briefly discussed.(author)
Neutron rich nuclei around 132Sn
International Nuclear Information System (INIS)
Bhattacharya, Sarmishtha
2016-01-01
The neutron rich nuclei with few particles or holes in 132 Sn have various experimental and theoretical interest to understand the evolution of nuclear structure around the doubly magic shell closure Z=50 and N=82. Some of the exotic neutron rich nuclei in this mass region are situated near waiting points in the r-process path and are of special astrophysical interest. Neutron rich nuclei near 132 Sn have been studied using fission fragment spectroscopy. The lifetime of low lying isomeric states have been precisely measured and the beta decay from the ground and isomeric states have been characterized using gamma-ray spectroscopy
Collective models of transition nuclei Pt. 2
International Nuclear Information System (INIS)
Dombradi, Zs.
1982-01-01
The models describing the even-odd and odd-odd transition nuclei (nuclei of moderate ground state deformation) are reviewed. The nuclear core is described by models of even-even nuclei, and the interaction of a single particle and the core is added. Different models of particle-core coupling (phenomenological models, collective models, nuclear field theory, interacting boson-fermion model, vibration nucleon cluster model) and their results are discussed. New developments like dynamical supersymmetry and new research trends are summarized. (D.Gy.)
Coulomb energy differences in mirror nuclei
International Nuclear Information System (INIS)
Lenzi, Silvia M
2006-01-01
By comparing the excitation energies of analogue states in mirror nuclei, several nuclear structure properties can be studied as a function of the angular momentum up to high spin states. They can be described in the shell model framework by including electromagnetic and nuclear isospin-non-conserving interactions. Calculations for the mirror energy differences in nuclei of the f 7/2 shell are described and compared with recent experimental data. These studies are extended to mirror nuclei in the upper sd and fp shells
International Nuclear Information System (INIS)
Oset, E.; Cabrera, D.; Li, Q.B.; Magas, V.K.; Vicente Vacas, M.J.
2005-01-01
We study the binding energy and the width of the Θ + in nuclei, associated to the KN and KπN components. The first one leads to negligible contributions while the second one leads to a sizeable attraction, enough to bind the Θ + in nuclei. Pauli blocking and binding effects on the KN decay reduce considerably the Θ + decay width in nuclei and medium effects associated to the KπN component also lead to a very small width, as a consequence of which one finds separation between the bound levels considerably larger than the width of the states
Is there chirality in atomic nuclei?
International Nuclear Information System (INIS)
Meng Jie
2009-01-01
Static chiral symmetries are common in nature, for example, the macroscopic spirals of snail shells, the microscopic handedness of certain molecules, and human hands. The concept of chirality in atomic nuclei was first proposed in 1997, and since then many efforts have been made to understand chiral symmetry and its spontaneous breaking in atomic nuclei. Recent theoretical and experimental progress in the verification of chirality in atomic nuclei will be reviewed, together with a discussion of the problems that await to be solved in the future. (authors)
Bubble nuclei in relativistic mean field theory
International Nuclear Information System (INIS)
Shukla, A.; Aberg, S.; Patra, S.K.
2011-01-01
Bubble nuclei are characterized by a depletion of their central density, i.e. the formation of the proton or neutron void and subsequently forming proton or neutron bubble nuclei. Possibility of the formation of bubble nuclei has been explored through different nuclear models and in different mass regions. Advancements in experimental nuclear physics has led our experimental access to many new shapes and structures, which were inaccessible hitherto. In the present paper, the possibility of observing nuclear bubble in oxygen isotopes, particularly for 22 O has been studied
Formation and decay of hot nuclei
International Nuclear Information System (INIS)
Tamain, B.
1992-09-01
The mechanisms involved in hot nuclei formation and decay and their eventual connexion with fundamental properties of nuclear matter are discussed, i.e. its equation of state is considered. After a brief review of the reactions in which hot nuclei can be formed, the variables which are used to describe them, the corresponding theoretical descriptions and their limits when extreme states are reached are discussed. Experimental evidences for hot nuclei formation are presented, with the corresponding decay properties used as signatures. (R.P.) 64 refs.; 25 figs.; 2 tabs
Hot nuclei: high temperatures, high angular momenta
International Nuclear Information System (INIS)
Guerreau, D.
1991-01-01
A review is made of the present status concerning the production of hot nuclei above 5 MeV temperature, concentrating mainly on the possible experimental evidences for the attainment of a critical temperature, on the existence of dynamical limitations to the energy deposition and on the experimental signatures for the formation of hot spinning nuclei. The data strongly suggest a nuclear disassembly in collisions involving very heavy ions at moderate incident velocities. Furthermore, hot nuclei seem to be quite stable against rotation on a short time scale. (author) 26 refs.; 12 figs
Evolution of planetary nebula nuclei
International Nuclear Information System (INIS)
Shaw, R.A.
1985-01-01
The evolution of planetary nebula nuclei (PNNs) is examined with the aid of the most recent available stellar evolution calculations and new observations of these objects. Their expected distribution in the log L-log T plane is calculated based upon the stellar evolutionary models of Paczynski, Schoenberner and Iben, the initial mass function derived by Miller and Scalo, and various assumptions concerning mass loss during post-main sequence evolution. The distribution is found to be insensitive both to the assumed range of main-sequence progenitor mass and to reasonable variations in the age and the star forming history of the galactic disk. Rather, the distribution is determined by the strong dependence of the rate of stellar evolution upon core mass, the steepness of the initial mass function, and to a lesser extent the finite lifetime of an observable planetary nebula. The theoretical distributions are rather different than any of those inferred from earlier observations. Possible observational selection effects that may be responsible are examined, as well as the intrinsic uncertainties associated with the theoretical model predictions. An extensive photometric and smaller photographic survey of southern hemisphere planetary nebulae (PNs) is presented
Shape nuclei and nuclear reactions
International Nuclear Information System (INIS)
Yushkov, A.V.
1975-01-01
Experimental methods for obtaining the nucleus shape parameters are reviewed throughout the period of 1955-1975. Spatial properties of a nucleus, which can be directly or indirectly measured, are determined. They include: parameters of nucleus localization in space; parameters characterizing the nucleus nonsphericity; parameters of the nucleus nonaxiality. Dimensional parameters of a nucleus, namely, radius R and surface ΔR are derived from electron scattering. The deformation sign is indirectly obtained in the experiments. Parameters of the nucleus shape, namely, the sign and magnitude of nuclear deformation are derived from the mean energy proton scattering by a coupled channels method. The only direct way of deriving the nucleus surface deformation signs is the method of the Blaire phase shift. Results on scattering of electrons, protons, and α-particles on light and medium nuclei are reported. Data on the nucleus shape can be also obtained from reactions with heavy ions. A difference between strong absorptions of incident particles of high and average energy by a nucleus is noted. Numerous diagrams illustrate experimental and theoretical results
International Nuclear Information System (INIS)
Beck, Christian
2012-01-01
Following the pioneering discovery of alpha clustering and of molecular resonances, the field of nuclear clustering is today one of those domains of heavy-ion nuclear physics that faces the greatest challenges, yet also contains the greatest opportunities. After many summer schools and workshops, in particular over the last decade, the community of nuclear molecular physicists has decided to collaborate in producing a comprehensive collection of lectures and tutorial reviews covering the field. This second volume follows the successful Lect. Notes Phys. 818 (Vol.1), and comprises six extensive lectures covering the following topics: - Microscopic cluster models - Neutron halo and break-up reactions - Break-up reaction models for two- and three-cluster projectiles - Clustering effects within the di-nuclear model - Nuclear alpha-particle condensates - Clusters in nuclei: experimental perspectives By promoting new ideas and developments while retaining a pedagogical style of presentation throughout, these lectures will serve as both a reference and an advanced teaching manual for future courses and schools in the fields of nuclear physics and nuclear astrophysics. (orig.)
Energy Technology Data Exchange (ETDEWEB)
Beck, Christian (ed.) [Strasbourg Univ. (France). Inst. Pluridiciplinaire Hubert Curien
2012-07-01
Following the pioneering discovery of alpha clustering and of molecular resonances, the field of nuclear clustering is today one of those domains of heavy-ion nuclear physics that faces the greatest challenges, yet also contains the greatest opportunities. After many summer schools and workshops, in particular over the last decade, the community of nuclear molecular physicists has decided to collaborate in producing a comprehensive collection of lectures and tutorial reviews covering the field. This second volume follows the successful Lect. Notes Phys. 818 (Vol.1), and comprises six extensive lectures covering the following topics: - Microscopic cluster models - Neutron halo and break-up reactions - Break-up reaction models for two- and three-cluster projectiles - Clustering effects within the di-nuclear model - Nuclear alpha-particle condensates - Clusters in nuclei: experimental perspectives By promoting new ideas and developments while retaining a pedagogical style of presentation throughout, these lectures will serve as both a reference and an advanced teaching manual for future courses and schools in the fields of nuclear physics and nuclear astrophysics. (orig.)
Integral nucleus-nucleus cross sections
International Nuclear Information System (INIS)
Barashenkov, V.S.; Kumawat, H.
2003-01-01
Expressions approximating the experimental integral cross sections for elastic and inelastic interactions of light and heavy nuclei at the energies up to several GeV/nucleon are presented. The calculated cross sections are inside the corridor of experimental errors or very close to it. Described in detail FORTRAN code and a numerical example of the cross section approximation are also presented
Directory of Open Access Journals (Sweden)
Sagaidak Roman
2017-01-01
Full Text Available The cross section data for fission and evaporation residue production in fusion reactions leading to nuclei from Po to Ra have been considered in a systematic way in the framework of the conventional barrier-passing (fusion model coupled with the statistical model. The cross section data obtained in very asymmetric projectile-target combinations can be described within these models rather well with the adjusted model parameters. In particular, one can scale and fix the macroscopic (liquid-drop fission barrier heights (FBHs for nuclei involved in the de-excitation of compound nuclei produced in the reactions. The macroscopic FBHs for nuclei from Po to Ra have been derived in the framework of such analysis and compared with the predictions of various theoretical models.
Proton optical potential and scattering matrix for tin nuclei at sub-coulomb energies
International Nuclear Information System (INIS)
Guzhovskij, B.Ya.; Dzyuba, B.M.
1981-01-01
A unified set of parameters of the proton optical potential (OP) for the n nuclei is searched for in the below-Coulomb-barrier energy range. The set must describe well the experimental data on the pn-reaction total cross sections and on the angular distributions of elastically scattered protons at E [ru
Understanding nuclei in the upper sd - shell
Energy Technology Data Exchange (ETDEWEB)
Sarkar, M. Saha; Bisoi, Abhijit; Ray, Sudatta [Nuclear Physics Division, Saha Institute of Nuclear Physics, Kolkata 700064 (India); Kshetri, Ritesh [Nuclear Physics Division, Saha Institute of Nuclear Physics, Kolkata 700064, India and Sidho-Kanho-Birsha University, Purulia - 723101 (India); Sarkar, S. [Indian Institute of Engineering Science and Technology, Shibpur, Howrah - 711103 (India)
2014-08-14
Nuclei in the upper-sd shell usually exhibit characteristics of spherical single particle excitations. In the recent years, employment of sophisticated techniques of gamma spectroscopy has led to observation of high spin states of several nuclei near A ≃ 40. In a few of them multiparticle, multihole rotational states coexist with states of single particle nature. We have studied a few nuclei in this mass region experimentally, using various campaigns of the Indian National Gamma Array setup. We have compared and combined our empirical observations with the large-scale shell model results to interpret the structure of these nuclei. Indication of population of states of large deformation has been found in our data. This gives us an opportunity to investigate the interplay of single particle and collective degrees of freedom in this mass region.
Perspectives of production of superheavy nuclei
Energy Technology Data Exchange (ETDEWEB)
Adamian, G. G.; Antonenko, N. V., E-mail: antonenk@theor.jinr.ru; Bezbakh, A. N.; Sargsyan, V. V. [Joint Institute for Nuclear Research, RU–141980 Dubna (Russian Federation); Scheid, W. [Institut für Theoretische Physik der Justus-Liebig-Universität, D–35392 Giessen (Germany)
2016-07-07
Possible ways of production of superheavies are discussed. Impact of nuclear structure on the production of superheavy nuclei in complete fusion reactions is discussed. The proton shell closure at Z = 120 is discussed.
Nuclear Computational Low Energy Initiative (NUCLEI)
Energy Technology Data Exchange (ETDEWEB)
Reddy, Sanjay K. [University of Washington
2017-08-14
This is the final report for University of Washington for the NUCLEI SciDAC-3. The NUCLEI -project, as defined by the scope of work, will develop, implement and run codes for large-scale computations of many topics in low-energy nuclear physics. Physics to be studied include the properties of nuclei and nuclear decays, nuclear structure and reactions, and the properties of nuclear matter. The computational techniques to be used include Quantum Monte Carlo, Configuration Interaction, Coupled Cluster, and Density Functional methods. The research program will emphasize areas of high interest to current and possible future DOE nuclear physics facilities, including ATLAS and FRIB (nuclear structure and reactions, and nuclear astrophysics), TJNAF (neutron distributions in nuclei, few body systems, and electroweak processes), NIF (thermonuclear reactions), MAJORANA and FNPB (neutrino-less double-beta decay and physics beyond the Standard Model), and LANSCE (fission studies).
Infrared Observations of Cometary Dust and Nuclei
Lisse, Carey
2004-01-01
This bibliography lists citations for publications published under the grant. Subjects of the publications include cometary dust, instellar and interplanetary dust, comet nuclei and comae, Comet Hale-Bopp, infrared observations of comets, mass loss, and comet break-up.
Superheavy nuclei: a relativistic mean field outlook
International Nuclear Information System (INIS)
Afanasjev, A.V.
2006-01-01
The analysis of quasi-particle spectra in the heaviest A∼250 nuclei with spectroscopic data provides an additional constraint for the choice of effective interaction for the description of superheavy nuclei. It strongly suggests that only the parametrizations which predict Z = 120 and N = 172 as shell closures are reliable for superheavy nuclei within the relativistic mean field theory. The influence of the central depression in the density distribution of spherical superheavy nuclei on the shell structure is studied. A large central depression produces large shell gaps at Z = 120 and N = 172. The shell gaps at Z = 126 and N = 184 are favoured by a flat density distribution in the central part of the nucleus. It is shown that approximate particle number projection (PNP) by means of the Lipkin-Nogami (LN) method removes pairing collapse seen at these gaps in the calculations without PNP
Searching for dual active galactic nuclei
Indian Academy of Sciences (India)
K. Rubinur
2018-02-09
Feb 9, 2018 ... Abstract. Binary or dual active galactic nuclei (DAGN) are expected from galaxy formation theories. How- ... cuss results from the multi-frequency Expanded Very .... mid-IR color using WISE observations where they have.
Lipkin-Nogami method for rotating nuclei
International Nuclear Information System (INIS)
Magierski, P.
1993-01-01
The extension of Lipkin-Nogami method to the case of rotating nuclei, where the short-range attraction acting between the nucleus (pairing free) plays a significant role for the coupling scheme is discussed. 7 refs, 6 figs
Collisions on relativistic nuclei: shock waves
International Nuclear Information System (INIS)
Gudima, K.K.; Toneev, V.D.
1976-01-01
Experiments are analysed which indicate the possible generation of shock waves in collisions of two nuclei. Another interpretation of these data is proposed and the concerned new experiments are discussed
Non-equilibrium entropy in excited nuclei
International Nuclear Information System (INIS)
Betak, E.
1991-06-01
The time-dependent behaviour of entropy in excited nuclei is investigated. In distinction to recent claims, it is shown that no self-organization is involved in pre-equilibrium nuclear reactions. (author). 9 refs.; 4 figs
ULTRA-RELATIVISTIC NUCLEI: A NEW FRONTIER
International Nuclear Information System (INIS)
MCLERRAN, L.
1999-01-01
The collisions of ultra-relativistic nuclei provide a window on the behavior of strong interactions at asymptotically high energies. They also will allow the authors to study the bulk properties of hadronic matter at very high densities
International Nuclear Information System (INIS)
EI-Nagdy, M.S.; Abdel-Waged, Kh; Abdel-Halim, S.M.; Khalil, E.I.
2000-01-01
The reaction cross sections for p, d, He, C, Mg and S beams with different chemical components of emulsion nuclei at 4.5 A GeV/c have been studied with high statistics, and were compared with the calculations according to Glauber model. The multiplicity distributions of shower produced particles from these interactions with light and heavy emulsion nuclei are analyzed in terms of the negative binomial and Poisson distribution laws
High energy particle interactions with nuclei
International Nuclear Information System (INIS)
Czyz, W.
1978-01-01
The recent interest in multiparticle production processes on nuclei was triggered by re-discovering their 'enigmatic simplicity' which has been known to cosmic ray physicists for over 20 years: the mean multiplicity and angular distributions of relativistic secondaries produced on nuclei do not differ markedly from what emerges from p-p collisions. The author considers how such reactions may provide a way of obtaining details of hadron structure. (Auth.)
Electro-magnetic properties of heavy nuclei
International Nuclear Information System (INIS)
Otsuka, Takaharu
1989-01-01
Two topics of electro-magnetic properties of heavy nuclei are discussed. The first topic is the M1 excitation from well-deformed heavy nuclei, and the other is the sudden increase of the isotope shift as a function of N in going away from the closed shell. These problems are considered in terms of the particle-number projected (Nilsson-) BCS calculation. (author)
Hot nuclei, limiting temperatures and excitation energies
International Nuclear Information System (INIS)
Peter, J.
1986-09-01
Hot fusion nuclei are produced in heavy ion collisions at intermediate energies (20-100 MeV/U). Information on the maximum excitation energy per nucleon -and temperatures- indicated by the experimental data is compared to the predictions of static and dynamical calculations. Temperatures around 5-6 MeV are reached and seem to be the limit of formation of thermally equilibrated fusion nuclei
Electron scattering and collective excitations in nuclei
International Nuclear Information System (INIS)
Goutte, D.
1989-01-01
Nuclear collective degrees of freedom are investigated through the study of the radial dependance of their wave function. Inelastic electron scattering is shown to be the appropriate tool to extract such a detailed information. Some recent results on spherical as well as deformed nuclei are discussed and the most recent extensions to the mean field approach are compared to these data in order to clarify the present status of our understanding of the dynamical properties of complex nuclei
Proton radioactivity from proton-rich nuclei
International Nuclear Information System (INIS)
Guzman, F.; Goncalves, M.; Tavares, O.A.P.; Duarte, S.B.; Garcia, F.; Rodriguez, O.
1999-03-01
Half-lives for proton emission from proton-rich nuclei have been calculated by using the effective liquid drop model of heavy-particle decay of nuclei. It is shown that this model is able to offer results or spontaneous proton-emission half-life-values in excellent agreement with the existing experimental data. Predictions of half-life-values for other possible proton-emission cases are present for null orbital angular momentum. (author)
Nuclei far off the stability line
International Nuclear Information System (INIS)
Fenyes, T.
1978-01-01
Theoretical and experimental aspects of the formation of some ''exotic'' nuclei far off the stability line were reviewed in addition to the relevant results of research in this field. Results in beta- and gamma-ray spectroscopy, heavy-ion-spectroscopy, achievements in the fields of measuring the atomic mass, the moment, and the radius of the nuclei as well as some astronomical aspects were described. (Z.P.)
Thomas Fermi model of finite nuclei
International Nuclear Information System (INIS)
Boguta, J.; Rafelski, J.
1977-01-01
A relativistic Thomas-Fermi model of finite-nuclei is considered. The effective nuclear interaction is mediated by exchanges of isoscalar scalar and vector mesons. The authors include also a self-interaction of the scalar meson field and the Coulomb repulsion of the protons. The parameters of the model are constrained by the average nuclear properties. The Thomas-Fermi equations are solved numerically for finite, stable nuclei. The particular case of 208 82 Pb is considered in more detail. (Auth.)
International Nuclear Information System (INIS)
Sitnik, I.M.
1995-01-01
The behaviour of the lightest nuclei break-up cross sections at zero angle has been analyzed in vicinity of the maximum. It is shown that asymmetry of cross sections relatively maximum is in conflict with nonrelativistic impulse approximation, but agrees well with one of relativistic approaches to describe this process. 10 refs., 9 figs
Vertical uniformity of cells and nuclei in epithelial monolayers.
Neelam, Srujana; Hayes, Peter Robert; Zhang, Qiao; Dickinson, Richard B; Lele, Tanmay P
2016-01-22
Morphological variability in cytoskeletal organization, organelle position and cell boundaries is a common feature of cultured cells. Remarkable uniformity and reproducibility in structure can be accomplished by providing cells with defined geometric cues. Cells in tissues can also self-organize in the absence of directing extracellular cues; however the mechanical principles for such self-organization are not understood. We report that unlike horizontal shapes, the vertical shapes of the cell and nucleus in the z-dimension are uniform in cells in cultured monolayers compared to isolated cells. Apical surfaces of cells and their nuclei in monolayers were flat and heights were uniform. In contrast, isolated cells, or cells with disrupted cell-cell adhesions had nuclei with curved apical surfaces and variable heights. Isolated cells cultured within micron-sized square wells displayed flat cell and nuclear shapes similar to cells in monolayers. Local disruption of nuclear-cytoskeletal linkages resulted in spatial variation in vertical uniformity. These results suggest that competition between cell-cell pulling forces that expand and shorten the vertical cell cross-section, thereby widening and flattening the nucleus, and the resistance of the nucleus to further flattening results in uniform cell and nuclear cross-sections. Our results reveal the mechanical principles of self-organized vertical uniformity in cell monolayers.
High spin spectroscopy for A ∼ 160 nuclei
International Nuclear Information System (INIS)
Yu, C.-H.
1989-01-01
Experimental routhians, alignments, band crossing frequencies, and the B(M1)/B(E2) ratios of the N = 90 isotopes and several light Lu (N = 90--96) isotopes are summarized and discussed in terms of shape changes. These systematic analyses show a neutron and proton number dependent deformations (both quadruple and γ deformations) for these light rare earth nuclei. The stability of the nuclear deformation with respect to β and γ is also found to be particle number dependent. Such particle number dependent shapes can be attributed to the different locations of the proton and neutron Fermi levels in the Nilsson diagrams. Configurations dependent shapes are discussed specially concerned the deformation difference between the proton h 9/2 1/2 - [541] and the high-K h 11/2 configurations. The observed large neutron band crossing frequencies in the h 9/2 1/2 - [541] configuration support the predicted large deformation of this configuration but can be reproduced by the cranked shell model calculation according to the predicted deformations. Lifetime measurement for 157 Ho, one of the nuclei that show a large ℎω c in the 1/2 - [541] band, indicates that deformation difference can only account for 20% of such shift in ℎω c . 55 refs., 12 figs
Microscopic description of α - particles interaction with ''7Li nuclei at low energies
International Nuclear Information System (INIS)
Burtebayev, N.; Basybekov, K.B.; Zhurynbayeva, G.S.; Sagindykov, Sh.Sh.;; Zhusupov, M.A.; Sakhiev, S.K.;
2001-01-01
The experimental data of α-particle elastic scattering on ''7Li nuclei are investigated within the framework of optical model by using of phenomenological and microscopical potentials. For construction of microscopical potentials double folding model and cluster folding model were used. The reproducing of cross-sections increasing on backward angles is achieved by the contribution of heavy stripping mechanism in scattering cross-section
Structure of neutron-rich nuclei
International Nuclear Information System (INIS)
Nazarewicz, W.
2000-01-01
Complete text of publication follows. The uncharted regions of the (N,Z) plane contain information that can answer many questions of fundamental importance for science: How many protons and neutrons can be clustered together by the strong interaction to form a bound nucleus? What are the proton and neutron magic numbers of the exotic nuclei? What are the properties of very short-lived exotic nuclei with extreme neutron-to-proton ratios? What is the effective nucleon-nucleon interaction in a nucleus that has a very large neutron excess? Nuclear life far from stability is different from that around the stability line; the promised access to completely new combinations of proton and neutron numbers offers prospects for new structural phenomena. The main objective of this talk is to discuss some of the challenges and opportunities of research with exotic nuclei. The covered topics will include: Theoretical challenges; Skins and halos in heavy nuclei; Shape coexistence in exotic nuclei; Beta-decays of neutron-rich nuclei. (author)
Major new sources of biological ice nuclei
Moffett, B. F.; Hill, T.; Henderson-Begg, S. K.
2009-12-01
Almost all research on biological ice nucleation has focussed on a limited number of bacteria. Here we characterise several major new sources of biogenic ice nuclei. These include mosses, hornworts, liverworts and cyanobacteria. Ice nucleation in the eukaryotic bryophytes appears to be ubiquitous. The temperature at which these organisms nucleate is that at which the difference in vapour pressure over ice and water is at or close to its maximum. At these temperatures (-8 to -18 degrees C) ice will grow at the expense of supercooled water. These organisms are dependent for their water on occult precipitation - fog, dew and cloudwater which by its nature is not collected in conventional rain gauges. Therefore we suggest that these organism produce ice nuclei as a water harvesting mechanism. Since the same mechanism would also drive the Bergeron-Findeisen process, and as moss is known to become airborne, these nuclei may have a role in the initiation of precipitation. The properties of these ice nuclei are very different from the well characterised bacterial nuclei. We will also present DNA sequence data showing that, although related, the proteins responsible are only very distantly related to the classical bacterial ice nuclei.
Elastic scattering, fusion, and breakup of light exotic nuclei
Energy Technology Data Exchange (ETDEWEB)
Kolata, J.J. [University of Notre Dame, Physics Department, Notre Dame, IN (United States); Guimaraes, V. [Universidade de Sao Paulo, Instituto de Fisica, Sao Paulo, SP (Brazil); Aguilera, E.F. [Instituto Nacional de Investigaciones Nucleares, Departamento de Aceleradores, Mexico, Distrito Federal (Mexico)
2016-05-15
The present status of fusion reactions involving light (A< 20) radioactive projectiles at energies around the Coulomb barrier (E<10 MeV per nucleon) is reviewed, emphasizing measurements made within the last decade. Data on elastic scattering (providing total reaction cross section information) and breakup channels for the involved systems, demonstrating the relationship between these and the fusion channel, are also reviewed. Similarities and differences in the behavior of fusion and total reaction cross section data concerning halo nuclei, weakly-bound but less exotic projectiles, and strongly-bound systems are discussed. One difference in the behavior of fusion excitation functions near the Coulomb barrier seems to emerge between neutron-halo and proton-halo systems. The role of charge has been investigated by comparing the fusion excitation functions, properly scaled, for different neutron- and proton-rich systems. Possible physical explanations for the observed differences are also reviewed. (orig.)
Continuum effects in the scattering of exotic nuclei
Energy Technology Data Exchange (ETDEWEB)
Druet, T. [Universite Libre de Bruxelles (ULB), Physique Quantique, C.P. 165/82, Brussels (Belgium); Universite Libre de Bruxelles (ULB), Physique Nucleaire Theorique et Physique Mathematique, Brussels (Belgium); Descouvemont, P. [Universite Libre de Bruxelles (ULB), Physique Nucleaire Theorique et Physique Mathematique, Brussels (Belgium)
2012-10-15
We discuss continuum effects in the scattering of exotic nuclei, and more specifically on the {sup 11}Be + {sup 64}Zn scattering. {sup 11}Be is a typical example of an exotic nucleus, with a low binding energy. Elastic, inelastic and breakup cross-sections of the {sup 11}Be + {sup 64}Zn system are computed in the Continuum Discretized Coupled Channel formalism, at energies near the Coulomb barrier. We show that converged cross-sections need high angular momenta as well as as large excitation energies in the wave functions of the projectile. Extensions to other systems are simulated by different collision energies, and by varying the binding energy of {sup 11}Be. (orig.)
Synthesis and decay process of superheavy nuclei with Z=119-122 via hot-fusion reactions
Energy Technology Data Exchange (ETDEWEB)
Ghahramany, N.; Ansari, A. [Shiraz University, Department of Physics and Biruni Observatory, College of Science, Shiraz (Iran, Islamic Republic of)
2016-09-15
In this research article attempts have been made to calculate the superheavy-nuclei synthesis characteristics including, the potential energy parameters, fusion probability, fusion and evaporation residue (ER) cross sections as well as, decay properties of compound nucleus and the residue nuclei formation probability for elements with Z=119-122 by using the hot-fusion reactions. It is concluded that, although a selection of double magic projectiles such as {sup 48}Ca with high binding energy, simplifies the calculations significantly due to spherical symmetric shape of the projectile, resulting in high evaporation residue cross section, unfortunately, nuclei with Z > 98 do not exist in quantities sufficient for constructing targets for the hot-fusion reactions. Therefore, practically our selection is fusion reactions with titanium projectile because the mass production of target nuclei for experimental purposes is more feasible. Based upon our findings, it is necessary, for new superheavy-nuclei production with Z > 119, to use neutron-rich projectiles and target nuclei. Finally, the maximal evaporation residue cross sections for the synthesis of superheavy elements with Z=119-122 have been calculated and compared with the previously founded ones in the literature. (orig.)
How far are we on the way to the superheavy nuclei?
International Nuclear Information System (INIS)
Muenzenberg, G.
1989-10-01
The discovery of the elements 107, 108, and 109 in a region of dominating shell stabilization is the most important step on the way to the superheavy nuclei in recent years. These experiments leading to the presently upper end of the periodic table were possible with the velocity filter SHIP to separate the heavy nuclei produced in complete fusion reactions of heavy ions. The identification of the unknown nuclei was established by α-α mother-daughter correlation of the nuclei decaying after the implantation into position sensitive surface-barrier detectors. With this method it is possible to identify even single nuclei of unknown isotopes unambiguously. The limits of sensitivity are production cross-sections of a few picobarns and about 2 μs of nuclear lifetime. With this method the elements 107, 108, and 109 were observed for the first time by their α-decay and identified unambiguously. For element 107 the isotopes with masses 261 and 262, for the element 108 the isotopes with masses 264 and 265, and for element 109 the isotope with mass 266 were found. The halflives range from 0.1 ms to 0.1 s. The highly fissile transactinide nuclei were produced in cold fusion of heavy ions using 207,208 Pb and 209 Bi targets, respectively, and 50 Ti, 54 Cr, or 58 Fe beams. The evaluation of the excitation functions for the production of very heavy evaporation residues shows a strong decrease above 25 MeV excitation energy caused by a destruction of the groundstate shell effects at high excitation energies. The strong competition of barrier transmission and survival probability results in rather narrow excitation functions and small production cross sections. The maximum cross section is observed close to the Coulomb barrier and corresponding to projectile energies near 5 MeV/u. (orig.) [de
Deuteron interaction with 124Sn nuclei at sub-barrier energies
Directory of Open Access Journals (Sweden)
Yu.N. Pavlenko
2015-04-01
Full Text Available The measurements of cross sections for deuteron elastic scattering and (d,p reaction on 124Sn nuclei have been performed with aim to study the features of sub-barrier deuteron interaction with heavy nuclei. Experimental data were obtained on the electrostatic Tandem accelerator EGP-10K of the Institute for Nuclear Research (Kyiv at the deuteron beam energies Ed = 4.0; 5.0 and 5.5 MeV. Cross sections of deuteron elastic scattering were calculated in approach where the deuteron interaction potential with heavy nuclei at sub-barrier energies has been constructed in the framework of single folding model using the complex dynamic polarization potential. It is shown that the account of finite deuteron size leads to the increasing the nuclear potential in outer region of interaction and significantly improves the description of the experimental data. The calculations of elastic scattering cross sections were performed without any variations of the nuclear potential parameters. The analysis of measured integral cross sections of the 124Sn(d,p reaction and calculated cross sections of deuteron breakup reaction 124Sn(d,pn124Sn shows the dominant contribution of the neutron transfer reaction in the processes of the formation of protons and elastic scattering cross sections.
Scaling laws and higher-order effects in Coulomb excitation of neutron halo nuclei
International Nuclear Information System (INIS)
Typel, S.; Baur, G.
2008-01-01
Essential properties of halo nuclei can be described in terms of a few low-energy constants. For neutron halo nuclei, analytical results can be found for wave functions and electromagnetic transition matrix elements in simple but well-adapted models. These wave functions can be used to study nuclear reactions; an especially simple and instructive example is Coulomb excitation. A systematic expansion in terms of small parameters can be given. We present scaling laws for excitation amplitudes and cross-sections. The results can be used to analyze experiments like 11 Be Coulomb excitation. They also serve as benchmark tests for more involved reaction theories. (orig.)
International Nuclear Information System (INIS)
Rotter, M.
1985-01-01
Part I and part II are presented of the contributions submitted to the International study meeting on physics with oriented nuclei and of papers from the International summer school on hyperfine interactions. The contributions and papers are devoted to the present status and further development of low temperature nuclear orientation of short-lived nuclei with emphasis on online techniques. The following topics are covered: nuclear orientation, NMR/ON, level mixing and level crossing resonances, laser spectroscopy, Moessbauer spectroscopy, polarization phenomena in low, medium and high energy physics, applications of hyperfine interaction techniques in nuclear physics, atomic physics, solid state physics, biology and materials research. (Z.J.)
Projected shell model study of yrast states of neutron-deficient odd-mass Pr nuclei
International Nuclear Information System (INIS)
Ibanez-Sandoval, A.; Ortiz, M. E.; Velazquez, V.; Galindo-Uribarri, A.; Hess, P. O.; Sun, Y.
2011-01-01
A wide variety of modern instruments allow us to study neutron-deficient nuclei in the A=130 mass region. Highly deformed nuclei have been found in this region, providing opportunities to study the deformed rotational bands. The description of the 125,127,129,131,133 Pr isotopes with the projected shell model is presented in this paper. Good agreement between theory and experiment is obtained and some characteristics are discussed, including the dynamic moment of inertia J (2) , kinetic moment of inertia J (1) , the crossing of rotational bands, and backbending effects.