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Sample records for 24mg 44ca 90zr

  1. Double γ decay in 90Zr

    The double γ decay between θ+n - θ+i of 90Zr was observed. The θ+n level was fed through the decay of 90 Sr. The experimental arrangement consisted of a double coincidence system between the two semiconductor detectors. (A.C.A.S.)

  2. Weak transition of 44Ca

    A study of the nuclear core contribution to the excited nuclear states was done, along with its theoretical evaluation and interpretation, in the light nuclei region. The 727 KeV gamma ray transition between the 1885 KeV O+ and 1157 KeV - 2+ states was detected, putting in evidence experimentally, the possibility of the 0+ state, characterized as core excitation, and found to be by + decay or electron capture from44,44mSc. The formation of the 2850 KeV state, due to 880 KeV transition from the 3667 KeV state, is re-discussed. The 564 KeV and 1684 KeV transitions from the 2850 KeV state to the 2285 KeV and 1157 KeV states, respectively, are also discussed. A new scheme is proposed for the 44Ca excited states. (Author)

  3. Pygmy dipole strength in 90Zr

    Schwengner, R; Tsoneva, N; Benouaret, N; Beyer, R; Erhard, M; Grosse, E; Junghans, A R; Klug, J; Kosev, K; Lenske, H; Nair, C; Schilling, K D; Wagner, A

    2008-01-01

    The dipole response of the N=50 nucleus 90Zr was studied in photon-scattering experiments at the electron linear accelerator ELBE with bremsstrahlung produced at kinetic electron energies of 7.9, 9.0, and 13.2 MeV. We identified 189 levels up to an excitation energy of 12.9 MeV. Statistical methods were applied to estimate intensities of inelastic transitions and to correct the intensities of the ground-state transitions for their branching ratios. In this way we derived the photoabsorption cross section up to the neutron-separation energy. This cross section matches well the photoabsorption cross section obtained from (gamma,n) data and thus provides information about the extension of the dipole-strength distribution toward energies below the neutron-separation energy. An enhancement of E1 strength has been found in the range of 6 MeV to 11 MeV. Calculations within the framework of the quasiparticle-phonon model ascribe this strength to a vibration of the excessive neutrons against the N = Z neutron-proton c...

  4. Gamma-gamma directional correlations in 90Zr

    Directional correlations of γγ cascades in 90Zr have been measured employing a twelve-channel goniometer. The spin and parity 7+ is assigned to the 5060.0 keV level. The multipole mixing ratios of the involved γ-ray transitions have been determined. The γ-ray transition probabilities for some transitions are calculated and compared with predictions of the shell model for the 90Zr nucleus. (Auth.)

  5. Isospin mixing in 24Mg

    We have used the #betta#-#betta# circular polarization (CP) correlation technique to measure the isospin-forbidden Fermi matrix element for the #betta#+ decay of 24Al to the 4+ T=1 state in 24Mg at E/sub x/=8.437 MeV. The 24Al activity was produced by bombarding a natural Mg target with 18 MeV protons. The #betta#-#betta# CP correlation was measured using a novel apparatus which featured good energy resolution in both the #betta# and #betta# arms. The CP sensitive #betta#-ray detector utilized a transmission-mode Compton polarimeter and a 12.7 cm x 15.2 cm NaI detector. The #betta# detector was a telescope with a 700 μm surface barrier detector and a 5.1 cm x 12.7 cm plastic scintillator. The #betta#-#betta# CP asymmetry A [defined by W(theta, t tilde) = 1 + t tilde v/c A tilde cos theta where t tilde is the photon helicity] was found to be A tilde = -0.145 +- 0.030. After applying a correction for feeding of the 8.437 MeV state from the analog state this value of A tilde corresponds to a charge dependent matrix element between the 9.5 MeV 4+T=1 and 8.4 MeV T=O levels of [+;O[H/sub CD/]4+;1>] = 106 +- 40 keV which is the largest matrix element of H/sub CD/ ever observed in #betta# decay. For comparison the charge dependent matrix element between the 9.5 MeV state and the 4.1 MeV 4+ state, previously measured in 24Na decays is only 5.4 +- 2.2 keV. Our exceptionally large value occurs because the 9.5 MeV T=1 and 8.4 MeV T=O states have very similar space and spin wavefunctions. This matrix element is consistent with predictions which ascribe the entire effect to Coulomb forces

  6. Producing a compound Nucleus via Inelastic Scattering: The 90Zr(alpha,alpha')90Zr* Case

    Escher, J E; Dietrich, F S

    2008-05-23

    In a Surrogate reaction a compound nucleus is produced via a direct reaction (pickup, stripping, or inelastic scattering). For a proper application of the Surrogate approach it is necessary to predict the resulting angular momentum and parity distribution in the compound nucleus. A model for determining these distributions is developed for the case of inelastic alpha scattering off a spherical nucleus. The focus is on obtaining a first, simple description of the direct-reaction process that produces the compound nucleus and on providing the basis for a more complete treatment of the problem. The approximations employed in the present description are discussed and the extensions required for a more rigorous treatment of the problem are outlined. To illustrate the formalism, an application to {sup 90}Zr({alpha},{alpha}{prime}){sup 90}Zr* is presented.

  7. Double gamma decay in 40Ca and 90Zr

    The rare double gamma decay of the first excited 0+ state in 40Ca and 90Zr has been measured with a segmented 4π NaI detector system, which allows suppression of the perturbing background due to positron annihilation in flight. In both cases the directional correlation of the two photons is found to be asymmetric around 900, which is explained by an interference of 2E1 and 2M1 transitions. The deduced M1 quenching factors agree with those from (e,e') and (p,p') measurements

  8. Pygmy dipole resonance and dipole polarizability in {sup 90}Zr

    Iwamoto, C.; Tamii, A.; Shima, T.; Hashimoto, T.; Suzuki, T.; Fujita, H.; Hatanaka, K. [Research Center for Nuclear Physics, Osaka University, Ibaraki, Osaka 567-0047 (Japan); Utsunomiya, H.; Akimune, H.; Yamagata, T.; Okamoto, A.; Kondo, T. [Department of Physics, Konan University, Okamoto 8-9-1, Higashinada, Kobe 658-8501 (Japan); Nakada, H. [Department of Physics, Graduate School of Science, Chiba University, Yayoi-cho 1-33, Inage, Chiba 263-8522 (Japan); Kawabata, T. [Department of Physics, Kyoto University, Kyoto 606-8502 (Japan); Fujita, Y. [Department of Physics, Osaka University, Toyonaka, Osaka, 560-0043 (Japan); Matsubara, H. [RIKEN Nishina Center, Wako, Saitama 351-0198 (Japan); Shimbara, Y.; Nagashima, M. [Department of Physics, Niigata University, Niigata 950-21-2 (Japan); Sakuda, M.; Mori, T. [Department of Physics, Okayama University, Okayama 900-0082 (Japan); and others

    2014-05-02

    Electric dipole (E1) reduced transition probability B(E1) of {sup 90}Zr was obtained by the inelastic proton scattering near 0 degrees using a 295 MeV proton beam and multipole decomposition analysis of the angular distribution by the distorted-wave Born approximation with the Hartree-Fock plus random-phase approximation model and inclusion of El Coulomb excitation, and the E1 strength of the pygmy dipole resonance was found in the vicinity of the neutron threshold in the low-energy tail of the giant dipole resonance. Using the data, we plan to determine the precise dipole polarizability α{sub D} which is defined as an inversely energy-weighted sum value of the elecrric dipole strength. The dipole polarizability is expected to constrain the symmetry energy term of the neutron matter equation of state. Thus systematical measurement of the dipole polarizability is important.

  9. Transfer reactions for the /sup 50/Ti + /sup 90/Zr system below the Coulomb barrier

    The analysis of quasielastic cross section data for the /sup 90/Zr projectile plus /sup 50/Ti target system shows that the probability for /sup 50/Ti(/sup 90/Zr, /sup 49/Ti)/sup 91/Zr, 1n-transfer reaction near the barrier is much larger than estimates based on semiclassical theory. The probability for /sup 50/Ti(/sup 90/Zr,/sup 51/V)/sup 89/Y, 1p-transfer reaction, on the other hand, agrees with the same theory. The internuclear distance where the 1n-transfer probability first deviates from tunneling predictions coincides with the threshold of the fusion barrier distribution deduced from the experimental fusion cross sections of the /sup 50/Ti+/sup 90/Zr system, suggesting a common mechanism for the large enhancement of 1n-transfer and fusion cross sections

  10. Experimental constraints on the $\\gamma$-ray strength function in $^{90}$Zr using partial cross sections of the $^{89}$Y(p,$\\gamma$)$^{90}$Zr reaction

    Netterdon, L; Goriely, S; Mayer, J; Scholz, P; Spieker, M; Zilges, A

    2015-01-01

    Partial cross sections of the $^{89}$Y(p,$\\gamma$)$^{90}$Zr reaction have been measured to investigate the $\\gamma$-ray strength function in the neutron-magic nucleus $^{90}$Zr. For five proton energies between $E_p=3.65$ MeV and $E_p=4.70$ MeV, partial cross sections for the population of seven discrete states in $^{90}$Zr have been determined by means of in-beam $\\gamma$-ray spectroscopy. Since these $\\gamma$-ray transitions are dominantly of $E1$ character, the present measurement allows an access to the low-lying dipole strength in $^{90}$Zr. A $\\gamma$-ray strength function based on the experimental data could be extracted, which is used to describe the total and partial cross sections of this reaction by Hauser-Feshbach calculations successfully. Significant differences with respect to previously measured strength functions from photoabsorption data point towards deviations from the Brink-Axel hypothesis relating the photo-excitation and de-excitation strength functions.

  11. Spin differences in the 90Zr compound nucleus induced by (p ,p') , (p ,d ) , and (p ,t ) surrogate reactions

    Ota, S.; Burke, J. T.; Casperson, R. J.; Escher, J. E.; Hughes, R. O.; Ressler, J. J.; Scielzo, N. D.; Thompson, I. J.; Austin, R. A. E.; Abromeit, B.; Foley, N. J.; McCleskey, E.; McCleskey, M.; Park, H. I.; Saastamoinen, A.; Ross, T. J.

    2015-11-01

    The effect of the production mechanism on the decay of a compound nucleus is investigated. The nucleus 90Zr was produced by three different reactions, namely 90Zr(p ,p') 90Zr , 91Zr(p ,d ) 90Zr , and 92Zr(p ,t ) 90Zr , which served as surrogate reactions for 89Zr(n ,γ ) . The spin-parity (Jπ) distributions of the states populated by these reactions were studied to investigate the surrogate reaction approach, which aims at indirectly determining cross sections for compound-nuclear reactions involving unstable targets such as 89Zr . Discrete γ rays, associated with transitions in 90Zr and 89Zr , were measured in coincidence with light ions for scattering angles of 25∘-60∘ and 90Zr excitation energies extending above the neutron separation energy. The measured transition systematics were used to gain insights into the Jπ distributions of 90Zr . The 90Zr(p ,p') reaction was found to produce fewer γ rays associated with transitions involving high spin states (J =6 -8 ℏ ) than the other two reactions, suggesting that inelastic scattering preferentially populates states in 90Zr that have lower spins than those populated in the transfer reactions investigated. The γ -ray production was also observed to vary by factors of 2-3 with the angle at which the outgoing particle was detected. These findings are relevant to the application of the surrogate reaction approach.

  12. (3He,t) reaction at 80MeV on 90Zr and 208Pb

    An experiment using the 80MeV 3He beam of the ISN cyclotron at Grenoble has been done on a target of 90Zr and another one of 208Bi. The 90Zr and 208Pb IAS angular distributions are fitted by DWBA calculations. For the previously reported Gamow Teller transition centered in 90Nb at 8.4MeV, two components are observed. The first one of M1 type is centered at 7.2MeV, the other one of unknown polarity at 9.7MeV

  13. Neutrons transition densities for the $2^+-8^+$ multiplet of states in $^{90}$Zr

    Onegin, M. S.; Plavko, A. V.

    2003-01-01

    The neutron transition densities of the $2^+-8^+$ levels in $^{90}$Zr were extracted in the process of analysing ({\\bf p},p') scattering at 400 Mev. Its comparison with the proton transition densities for these levels was undertaken. The radial shapes of the experimental neutron and proton transition densities for each state were found to be different.

  14. Two-photon radiation in the 90Zr 0+→0+ transition

    An experiment on studying two-photon radiation in 0+→0+-transition with 1.76 MeV of 90Zr is described. Ratio of two-photon process and pair conversion probabilities Wγγ/Wπ=(7.4±1.4)x10-4 is obtained

  15. Vibrational thermodynamics of Fe90Zr7B3 nanocrystalline alloy from nuclear inelastic scattering

    Stankov, S.; Miglierini, M.; Chumakov, A. I.;

    2010-01-01

    Recently we determined the iron-partial density of vibrational states (DOS) of nanocrystalline Fe(90)Zr(7)B(3) (Nanoperm), synthesized by crystallization of an amorphous precursor, for various stages of nanocrystallization separating the DOS of the nanograins from that of the interfaces [S. Stank...

  16. Deuteron excitation of the isoscalar breathing mode resonance in 90Zr, 120Sn, 208Pb

    With the new 108 MeV deuteron beam of the Orsay synchrocyclotron and the new experimental set up which allow measurements without background for angles as small as 40, a systematic study of the breathing mode has been undertaken and the results on 90Zr, 120Sn and 208Pb are reported

  17. Flashing coherently rotating carbon sticks in $^{24}$Mg+$^{24}$Mg collision

    Zhao, M H; Merlo, O; Huang, M R; Li, Y; Wang, J S

    2013-01-01

    We analyze quasi-periodic oscillations in the angle-averaged ($\\Delta\\theta_{cm}\\simeq 90^\\circ\\pm 25^\\circ $)excitation functions for the $^{24}Mg+^{24}Mg$ elastic-inelastic scattering and $\\alpha$-transfer channels on the energy interval $E_{cm}=44.86-47.76$ MeV.The period of the energy structures, $\\simeq$0.81 MeV, is interpreted as inverse half-period ($\\simeq 5\\times 10^{-21}$ sec.) of coherent rotation of highly excited short-lived ($\\simeq 3.6\\times 10^{-21}$ sec.) chain of a length $\\simeq 30$ fm. The rotational wave packet coherence survives (i) the energy relaxation (fully mixing ergodic dynamics) for the strongly overlapping states with fixed total spins and (ii) the strong distortion of the motion upon a change of the total spin.The present discussion leads us to the question: Is rotational coherence of large molecules necessarily destroyed in the conventionally statistical limit of structureless (non-selective) continuum under the conditions of complete intramolecular energy redistribution and vi...

  18. 16O+8Be cluster structure in 24Mg

    16O + 8Be cluster structure in 24Mg has been identified by observing the breakup into ground state 160 and 8Be fragments following inelastic scattering of 24Mg projectiles. The spectrum of states observed is compared to that previously measured in the 12C + 12C breakup channel to obtain information on the partial decay widths. (author)

  19. Study of the neutron decay of isoscalar electric giant resonances in the nucleus 90Zr

    The present thesis studies mainly the decay of the giant resonance region in 90Zr by means of a coincidence experiment which was performed at the 6Li beam of the Karlsruhe Isochronous Cyclotron. After excitation by inelastic scattering especially the neutron decay of the giant monopole and quadrupole resonance was observed by means of a (6Li,6Li'n) coincidence measurement. One aim of this experiment was to determine the relative branching ratios of the neutron decay from the region of the giant quadrupole resonance to the single low-lying states of 89Zr. In order to obtain an average over the angular correlation function for L>2 the decay neutrons were spectroscoped in 16 angles. The evaluation of the experiments yielded important results for the understanding of the giant resonances in heavy nuclei. The giant monopole and quadrupole resonances in 90Zr decay dominantly statistically. (orig./HSI)

  20. Neutron-/sup 90/Zr mean field from a dispersive optical model analysis

    Elastic scattering cross sections have been measured for 8, 10, and 24 MeV neutrons incident on /sup 90/Zr. These measurements, together with other neutron elastic scattering and total cross section data available up to 29 MeV, are used in grid searches to obtain an optical model potential which contains a dispersion relation term. This potential is then extrapolated toward negative energies to predict bound single-particle state properties. An overall good description of the data at positive and negative energies is achieved

  1. Exchange interactions in (FeT)90Zr10(T=Ru,Mn) metallic glasses (abstract)

    Recently there have been several theoretical reports about models of amorphous transition metal alloys which take into account the fluctuations of local magnetic moments due to structural disorder. It is predicted that the local atomic moment on an atom depends on the number of first near neighbors with short distances (contracted atoms) and it could be positive, negative, or negligible. An amorphous Fe endash Zr system could be a typical system to study these features which have a key role in determining the magnetic structure. Fe90Zr10 orders ferromagnetically at 230 K and exhibits a mixed state at T90Zr10. Mn is known to couple antiferromagnetically (AF) to Fe while Ru is expected to be nonmagnetic. We find that Mn reduces the Curie temperature (Tc) gradually while the spin freezing temperature (Tf) remains nearly constant. However, in the case of Ru, Tf drastically increases and 5 at.% Ru drives the system to a clear spin glass state. Hyperfine field studies show gradual evolution of AF coupled spins and their distribution, pointing out the existence of a well defined bimodal distribution. Fe endash Fe exchange is believed to become antiferromagnetic for Fe endash Fe distances 2Zr which is a closed packed structure). We propose that the dilution of Fe moment and the band modifications due to Ru substitution seemed to promote antiferromagnetic coupling in a Fe endash Zr system. copyright 1997 American Institute of Physics

  2. Alpha-cluster states populated in 24Mg + 12C

    Charged particle and γ-decays in light α-like nuclei are investigated for 24Mg +12C. Various theoretical predictions for the occurrence of superdeformed and hyperdeformed bands associated with resonance structures with low spin are presented. The inverse kinematics reaction 24Mg +12C is studied at Elab(24Mg) = 130 MeV. Exclusive data were collected with the Binary Reaction Spectrometer in coincidence with EUROBALL IV installed at the VIVITRON Tandem facility at Strasbourg. Specific structures with large deformation were selectively populated in binary reactions and their associated γ-decays studied. Coincident events from α-transfer channels were selected by choosing the excitation energy or the entry point via the two-body Q-values. The analysis of the binary reaction channels is presented with a particular emphasis on 20Ne-γ and 16O-γ coincidences. (author)

  3. Molecular resonances and the Jacobi shape transition: the case of 24Mg+24Mg and 48Cr

    A fast rotating 48Cr is predicted to be highly prolate and deformed after a Jacobi shape transition and just before fission. In this article, it is proposed that an arrow and high spin 24Mg+24Mg resonance corresponds to the formation of this exotic 48Cr. Moreover the 24Mg+24Mg reaction has been studied at the Legnaro Tandem at a CM bombarding energy of 45.7 MeV, where a narrow and high spin resonance has been reported previously. To establish the connection between the resonance and a molecular state of 48Cr, the decay of the resonance into the inelastic and fusion-evaporation channels has been investigated. The ON and OFF resonance decay yields have been measured using, for the inelastic channels, the fragment spectrometer PRISMA and the gamma array CLARA, and, for the fusion-evaporation channels, the Si array EUCLIDES and the gamma array GASP. Strong resonant effects have been observed in the inelastic channels involving the 2+ and 4+ states of the 24Mg ground state (g.s.) band. Weaker effects are also seen in certain fusion-evaporation channels. Both results will be discussed here. (authors)

  4. Total reaction cross sections for 8Li + 90Zr at near-barrier energies

    Total reaction cross sections for the radioactive nucleus 8Li on 90Zr are reported at the near-barrier energies of 18.5 and 21.5MeV, derived from quasi-elastic scattering measurements. An analysis of the quasi-elastic scattering results is performed within an optical model framework using the BDM3Y1 interaction and total reaction cross sections are deduced. These quantities, appropriately reduced, are compared with previous data obtained in elastic scattering measurements with well and weakly bound projectiles on various targets and a formula for predicting total reaction cross sections with an uncertainty of ∝ 20 % is obtained. Further on, the ratios of direct to total reaction cross sections are estimated for 6,8Li on various targets and are compared with CDCC or CRC calculations. The energy dependence of the optical potential is also discussed. (orig.)

  5. Gamow-Teller Resonance of 90Zr in a Relativistic Approach

    马中玉; 陈宝秋

    2003-01-01

    We establish the formalism of nuclear spin-isospin excitations, especially the Gamow-Teller resonance in a fully consistent relativistic random-phase approximation. A relativistic form of the Landau-Migdal parameter g′ is adopted as a residual spin-isospin correlation force. In the non-relativistic limit it reproduces the excitation energy of the giant Gamow-Teller resonance state obtained in the non-relativistic model. The Gamow-Teller resonance for finite nuclei is investigated in a relativistic approach for the first time. It is found that the Ikeda sum rule of90Zr is quenched about 8% in the Hartree as well as the correlated strengths due to the poles of the negative Dirac states at energies above 1 GeV.

  6. Estimated 55Mn and 90Zr cross section covariances in the fast neutron energy region

    Pigni,M.T.; Herman, M.; Oblozinsky, P.

    2008-06-24

    We completed estimates of neutron cross section covariances for {sup 55}Mn and {sup 90}Zr, from keV range to 25 MeV, considering the most important reaction channels, total, elastic, inelastic, capture, and (n,2n). The nuclear reaction model code EMPIRE was used to calculate sensitivity to model parameters by perturbation of parameters that define the optical model potential, nuclear level densities and strength of the pre-equilibrium emission. The sensitivity analysis was performed with the set of parameters which reproduces the ENDF/B-VII.0 cross sections. The experimental data were analyzed and both statistical and systematic uncertainties were extracted from almost 30 selected experiments. Then, the Bayesian code KALMAN was used to combine the sensitivity analysis and the experiments to obtain the evaluated covariance matrices.

  7. Structure of isobaric analog states in 91Nb populated by the 90Zr(a,t) reaction

    Van der Molen, H K T; Van den Berg, A M; Daito, I; Fujimura, H; Fujita, Y; Fujiwara, M; Harakeh, M N; Ihara, F; Inomato, T; Ishibashi, K; Jänecke, J; Kalantar-Nayestanaki, N; Laurent, H; Lhenry, I; O'Donnell, T W; Rodin, V A; Tamii, A; Toyokawa, H; Urin, M H; Yoshida, H; Yosoi, M

    2001-01-01

    Decay via proton emission of isobaric analog states (IAS's) in $^{91}{Nb}$ was studied using the $^{90}{Zr}(\\alpha,t)$ reaction at $E_\\alpha$=180 MeV. This study provides information about the damping mechanism of these states. Decay to the ground state and low-lying phonon states in $^{90}{Zr}$ was observed. The experimental data are compared with theoretical predictions wherein the IAS `single-particle' proton escape widths are calculated in a continuum RPA approach. The branching ratios for decay to the phonon states are explained using a simple model.

  8. Neutron inelastic cross section measurements for 24Mg

    OLACEL A.; Borcea, C.; DESSAGNE Philippe; Kerveno, M.; NEGRET A.; PLOMPEN Arjan

    2014-01-01

    The gamma production cross sections from the neutron inelastic scattering on 24Mg were measured for neutron energies up to 18 MeV at GELINA (Geel Linear Accelerator), the neutron source operated by EC-JRC-IRMM, Belgium. The level cross section and the total inelastic cross section were determined. We used the GAINS (Gamma Array for Inelastic Neutron Scattering) spectrometer with 7 large volume HPGe detectors placed at 110◦ and 150◦ with respect to the beam direction. The neutron flux was dete...

  9. Neutron capture cross section of $^{90}$Zr Bottleneck in the s-process reaction flow

    Tagliente, G; Milazzo, P M; Moreau, C; Aerts, G; Abbondanno, U; Alvarez, H; Alvarez-Velarde, F; Andriamonje, Samuel A; Andrzejewski, J; Assimakopoulos, Panayiotis; Audouin, L; Badurek, G; Baumann, P; Bečvář, F; Berthoumieux, E; Bisterzo, S; Calviño, F; Calviani, M; Cano-Ott, D; Capote, R; Carrapiço, C; Cennini, P; Chepel, V; Chiaveri, Enrico; Colonna, N; Cortés, G; Couture, A; Cox, J; Dahlfors, M; David, S; Dillman, I; Domingo-Pardo, C; Dridi, W; Durán, I; Eleftheriadis, C; Embid-Segura, M; Ferrant, L; Ferrari, A; Ferreira-Marques, R; Furman, W; Gallino, R; Gonçalves, I; Gonzalez-Romero, E; Gramegna, F; Guerrero, C; Gunsing, F; Haas, B; Haight, R; Heil, M; Herrera-Martínez, A; Igashira, M; Jericha, E; Käppeler, F; Kadi, Y; Karadimos, D; Karamanis, D; Kerveno, M; Köhler, P; Kossionides, E; Krtička, M; Lamboudis, C; Leeb, H; Lindote, A; Lopes, I; Lozano, M; Lukic, S; Marganiec, J; Marrone, S; Martínez, T; Massimi, C; Mastinu, P; Mengoni, A; Mosconi, M; Neves, F; Oberhummer, Heinz; O'Brien, S; Pancin, J; Papachristodoulou, C; Papadopoulos, C; Paradela, C; Patronis, N; Pavlik, A; Pavlopoulos, P; Perrot, L; Pigni, M T; Plag, R; Plompen, A; Plukis, A; Poch, A; Praena, J; Pretel, C; Quesada, J; Rauscher, T; Reifarth, R; Rubbia, Carlo; Rudolf, G; Rullhusen, P; Salgado, J; Santos, J; Sarchiapone, L; Savvidis, I; Stéphan, C; Taín, J L; Tassan-Got, L; Tavora, L; Terlizzi, R; Vannini, G; Vaz, P; Ventura, A; Villamarín, D; Vincente, M, C; Vlachoudis, V; Vlastou, R; Voss, F; Walter, S; Wendler, H; Wiescher, M; Wisshak, K

    2008-01-01

    The neutron capture cross sections of the Zr isotopes have important implications in nuclear astrophysics and for reactor design. The small cross section of the neutron magic nucleus 90Zr, which accounts for more than 50% of natural zirconium represents one of the key isotopes for the stellar s-process, because it acts as a bottleneck in the neutron capture chain between the Fe seed and the heavier isotopes. The same element, Zr, also is an important component of the structural materials used in traditional and advanced nuclear reactors. The (n,γ) cross section has been measured at CERN, using the n_TOF spallation neutron source. In total, 45 resonances could be resolved in the neutron energy range below 70 keV, 10 being observed for the first time thanks to the high resolution and low backgrounds at n_TOF. On average, the Γγ widths obtained in resonance analyses with the R-matrix code SAMMY were 15% smaller than reported previously. By these results, the accuracy of the Maxwellian averaged cross section f...

  10. 89 Zr(n,γ)90 Zr from a surrogate reaction approach

    Ota, Shuya; Burke, J. T.; Casperson, R. J.; Escher, J. E.; Hughes, R. O.; Ressler, J. J.; Scielzo, N. D.; Thompson, I.; Austin, R. A. E.; McCleskey, E.; McCleskey, M.; Saastamoinen, A.; Ross, T.

    2015-04-01

    While recent studies have demonstrated the validity of the surrogate reaction approach for studying fission cross sections of short-lived actinides, its applicability for (n, γ) is still under investigation. We studied the γ-decay of 90 Zr produced by 91 Zr(p,d) and 92 Zr(p,t) in order to infer the 89 Zr(n, γ) cross sections. The experiments were carried out at the K150 Cyclotron facility at Texas A&M University with a 28.5-MeV proton beam. The reaction deuterons and tritons were measured at forward angles of 30-60° with the STARS (Silicon Telescope Array for Reaction Studies) array of three segmented Micron S2 silicon detectors. Compound nuclei with energies up to a few MeV above the neutron separation thresholds were populated. The coincident γ-rays were measured with the LiTeR (Livermore Texas Richmond) array of five Compton-suppressed HPGe clovers. We will present results of γ-emission probabilities of 89 Zr(n, γ) and some theoretical discussions. This work was performed under the auspices of the US Department of Energy by Lawrence Livermore National Laboratory under Contract No. DE-AC52- 07NA27344. One of the authors, S. O. is supported by JSPS Postdoctoral Fellowship for Research Abroad.

  11. Hot fusion-evaporation cross sections of 44Ca-induced reactions with lanthanide targets

    Werke, T. A.; Mayorov, D. A.; Alfonso, M. C.; Tereshatov, E. E.; Folden, C. M.

    2015-11-01

    Background: Previously reported cross sections of 45Sc-induced reactions with lanthanide targets are much smaller than 48Ca-induced reactions on the same targets. 44Ca is one proton removed from 45Sc and could be used to produce nuclei with a relative neutron content between those produced in the 45Sc- and 48Ca-induced reactions. Purpose: As part of a systematic investigation of fusion-evaporation reactions, cross sections of 44Ca-induced reactions on lanthanide targets were measured. These results are compared to available data for 48Ca- and 45Sc-induced fusion-evaporation cross sections on the same lanthanide targets. Collectively, these data provide insight into the importance of the survival against fission of excited compound nuclei produced near spherical shell closures. Methods: A beam of 6+Ca at an energy of ≈5 MeV /u was delivered by the K500 superconducting cyclotron at the Cyclotron Institute at Texas A&M University. The desired evaporation residues were selected by the Momentum Achromat Recoil Spectrometer and identified via their characteristic α -decay energies. Excitation functions for the 44Ca+158Gd ,159Tb, and 162Dy reactions were measured at five or more energies each. A theoretical model was employed to study the fusion-evaporation process. Results: The 44Ca-induced reactions have x n cross sections that are two orders of magnitude larger than 45Sc-induced reactions but two orders of magnitude smaller than 48Ca-induced reactions on the same targets. Proton emission competes effectively with neutron emission for the 44Ca+159Tb and 162Dy reactions. The maximum 4 n cross sections in the 44Ca+158Gd ,159Tb, and 162Dy reactions were 2100 ± 230 ,230 ± 20 , and 130 ±20 μ b , respectively. The 44Ca+158Gd and 159Tb cross sections are in good agreement with the respective cross bombardments of 48Ca+154Gd and 45Sc+158Gd once differences in capture cross sections and compound nucleus formation probabilities are corrected for. Conclusions: Excitation

  12. Nuclear structure of 88Sr and 90Zr investigated by (e,e') and (p,p') reactions

    In this thesis the results are presented and discussed from two experiments, performed to investigate the nuclear structure of two N = 50 nuclei: a high resolution inelastic proton scattering experiment on 90Zr, described in chapter II, and a high resolution inelastic electron scattering experiment on 88Sr, described in chapters III and IV. The results obtained in the 88Sr(e,e') experiment for the 1+ state at 3.486 MeV excitation energy are described separately in chapter V. The 90Zr(p,p') experiment was performed at a bombarding energy of 25 MeV with a resolution of 12 to 16 keV. The 88Sr(e,e') measurements were performed at two laboratories with an overall resolution between 20 and 60 keV. (Auth.)

  13. Photon-induced multiple particle emissions of 90Zr and natZr from 10 to 140 MeV

    A comprehensive analysis of electrodisintegration yields of protons on 90Zr is proposed taking into account the giant dipole resonance, isovector giant quadrupole resonance (IVGQR), and quasideuteron contributions to the total photoabsorption cross section from 10 to 140 MeV. The calculation applies the MCMC intranuclear cascade to address the direct and pre-equilibrium emissions and another Monte Carlo-based algorithm to describe the evaporation step. The final results of the total photoabsorption cross section for 90Zr and relevant decay channels are obtained by fitting the (e,p) measurements from the National Bureau of Standards and show that multiple proton emissions dominate the photonuclear reactions at higher energies. These results provide a consistent explanation for the exotic and steady increase of the (e,p) yield and also a strong evidence of a IVGQR with a strength parameter compatible with the E2 energy-weighted sum rule. The inclusive photoneutron cross sections for 90Zr and natZr, derived from these results and normalized with the (e,p) data, are in agreement within 10% with both Livermore and Saclay data up to 140 MeV

  14. Comparison of Optical Models for 400 MeV alpha scattering off 90Zr and 92Mo

    Jones, Daniel; Howard, Kevin; Garg, Umesh; Senyigit, Menekse

    2015-10-01

    Nuclear incompressibility is an important parameter governing the equation of state of nuclear matter. From the measurable centroid energies of the Isoscalar Giant Monopole Resonance (ISGMR), the incompressibility of nuclear matter can be calculated. The first necessary step is to fit elastic scattering angular distributions for a particular reaction and test the obtained model dependent parameters by calculating low-lying discrete state distributions for target nuclei. This study tests the suitability of two optical models to reproduce the angular distributions of differential cross sections from elastic and inelastic scattering of 400-MeV alpha particles. The first model utilizes a single folded potential for both the real and imaginary volume terms, and the second utilizes a single folded potential for the real volume term, and a phenomenological Woods-Saxon potential for the imaginary volume term. The elastic distributions for two heavy isotopes, 90Zr and 92Mo, are analyzed and the best parameter sets for each are shown. From this comparison, it is concluded that the second model, the so called ``hybrid model,'' is better able to reproduce the angular distributions for both 90Zr and 92Mo. Future work will include the Multipole Decomposition Analysis (MDA) for each reaction. NSF/REU Program at Notre Dame.

  15. Dipole strength in {sup 89}Y and {sup 90}Zr up to the neutron-separation energy

    Schwengner, R.; Beyer, R.; Doenau, F.; Erhard, M.; Junghans, A.R.; Klug, J.; Kosev, K.; Nair, C.; Schilling, K.D.; Wagner, A. [Forschungszentrum Dresden-Rossendorf, 01314 Dresden (Germany); Rusev, G. [Forschungszentrum Dresden-Rossendorf, 01314 Dresden (Germany)]|[Duke University, Durham, NC 27708 (United States); Tsoneva, N. [Universitaet Giessen, 35392 Giessen (Germany); Benouaret, N. [Forschungszentrum Dresden-Rossendorf, 01314 Dresden (Germany)]|[Universite d' Alger, 16111 Alger, Algerie (Algeria); Grosse, E. [Forschungszentrum Dresden-Rossendorf, 01314 Dresden (Germany)]|[Technische Universitaet Dresden, 01062 Dresden (Germany)

    2008-07-01

    Dipole and quadrupole excitations in the semimagic N=50 nuclei {sup 89}Y and {sup 90}Zr were investigated at the superconducting electron linear accelerator ELBE with bremsstrahlung produced at electron energies from 9 to 13 MeV. About 200 {gamma} transitions in {sup 89}Y and 180 in {sup 90}Zr were identified up to about 11 and 12 MeV, respectively. Statistical methods were applied to estimate the contributions of inelastic transitions and to correct the intensities of the ground-state transitions for their branching ratios. The photoabsorption cross sections obtained in this way provide information about the dipole-strength function on the tail of the giant dipole resonance (GDR) towards energies below the neutron-separation energy. We observed extra dipole strength with respect to a smooth extrapolation of the GDR in the energy range from about 6 - 11 MeV. The observed extra strength is compared with results of calculations within the Quasiparticle-Phonon Model, which also make predictions about the nature of the strength.

  16. Nuclear Structure of the Closed Subshell Nucleus 90Zr Studied with the (n,n'(gamma)) Reaction

    Garrett, P E; Younes, Y; Becker, J A; Bernstein, L A; Baum, E M; DiPrete, D P; Gatenby, R A; Johnson, E L; McGrath, C A; Yates, S W; Devlin, M; Fotiades, N; Nelson, R O; Brown, B A

    2003-06-12

    States in {sup 90}Zr have been observed with the (n,n{prime}{gamma}) reaction using both spallation and monoenergetic accelerator-produced neutrons. A scheme comprised of 81 levels and 157 transitions was constructed concentrating on levels below 5.6 MeV in excitation energy. Spins have been determined by considering data from all experimental studies performed for {sup 90}Zr. Lifetimes have been deduced using the Doppler-shift attenuation method for many of the states and transition rates have been obtained. A spherical shell-model interpretation in terms of particle-hole excitations assuming a {sup 88}Sr closed core is given. In some cases, enhancements in B(M1) and B(E2) values are observed that cannot be explained by assuming simple particle-hole excitations. Shell-model calculations using an extended f pg-shell model space reproduce the spectrum of excited states very well, and the gross features of the B(M1) and B(E2) transition rates. Transition rates for individual levels show discrepancies between calculations and experimental values.

  17. Very low field ac-response at the loss of long range magnetic order in amorphous Fe90Zr10

    Low temperature ac-susceptibility measurements over 5 decades of ac-field (0.08-8000 A/m) have been carried out on amorphous ribbons of Fe90Zr10 and Fe91Zr9. The authors find that at very low fields (0.8 to 24 A/m) ac-response measurements eliminate the influence of domain and domain wall motion, the well known Hopkinson peak effects, to reveal clearly the reentrant characteristics. With such studies a reentrant freezing temperature Taf is unambiguously revealed with an evident knee in χ'(T) and a corresponding well defined peak in χ double-prime(T). The latter is found to be independent of the applied field (0.8 to 8 A/m) while being weakly dependent on the frequency (10--1,000 Hz). They thus find Tsf to be 25 K and 40 K respectively for Fe90Zr10 and Fe91Zr9 amorphous ribbons

  18. Reaction cross sections for protons on {sup 12}C, {sup 40}Ca, {sup 90}Zr and {sup 208}Pb at energies between 80 and 180 MeV

    Auce, A.; Ingemarsson, A.; Johansson, R. [and others

    2005-04-01

    Results of reaction cross section measurements on {sup 12}C, {sup 40}Ca, {sup 90}Zr and {sup 208}Pb at incident proton energies between 80 and 180 MeV and for {sup 58}Ni at 81 MeV are presented. The experimental procedure is described and the results are compared with earlier measurements and predictions using macroscopic and microscopic models.

  19. α-cluster model for the multiple emission of particles in the reaction 90Zr (e, α)

    We present a methodology based on the model of photoabsorption by a cluster N- α for a better understanding of the puzzling steady increase behavior of the 90 Zr (e, α) yield obtained experimentally in the energy range of the giant dipole resonance (RDG) and the quasi-deuteron (QD).The calculation takes into account the emission of protons, neutrons and alpha particles in the framework of the reaction (which was used for the Intranuclear Cascade model (MCMC)). The statistical decay of the compound nucleus is described by Monte Carlo techniques in terms of competition between evaporation of particles (p, n, d, α, 3 He t) and nuclear fission, but for our specific case (the reaction and + Zr 90 in an energy range between 20 and 140 MeV) the fission channel does not have a high probability of occurrence. The results reproduce quite successfully the experimental data, suggesting that pre-equilibrium emission of alpha particles are essential for the interpretation of this exotic increase of the cross sections. (Author)

  20. 87Y(n,γ and 89,90Zr(n,γ cross sections from a surrogate reaction approach

    Ota Shuya

    2015-01-01

    Full Text Available The surrogate reaction approach is an indirect method for determining nuclear reaction cross sections which cannot be measured directly or predicted reliably. While recent studies demonstrated the validity of the surrogate reaction approach for studying fission cross sections for short-lived actinides, its applicability for radiative neutron capture reactions ((n,γ is still under investigation. We studied the γ decay of excited 88Y and 90,91Zr nuclei produced by 89Y(p,d, 91Zr(p,d, and 92Zr(p,d reactions, respectively, in order to infer the 87Y(n,γ and 89, 90Zr(n,γ cross sections. The experiments were carried out at the K150 Cyclotron facility at Texas A&M University with a 28.5-MeV proton beam. The reaction deuterons were measured at forward angles of 25-60° with the array of three segmented Micron S2 silicon detectors. The compound nuclei with energies up to a few MeV above the neutron separation thresholds were populated. The coincident γ-rays were measured with the array of five Compton-suppressed HPGe clover detectors.

  1. 87Y(n,γ) and 89,90Zr(n,γ) cross sections from a surrogate reaction approach

    Ota, Shuya; Burke, J. T.; Casperson, R. J.; Escher, J. E.; Hughes, R. O.; Ressler, J. J.; Scielzo, N. D.; Thompson, I.; Austin, R. A. E.; McCleskey, E.; McCleskey, M.; Saastamoinen, A.; Ross, T.

    2015-05-01

    The surrogate reaction approach is an indirect method for determining nuclear reaction cross sections which cannot be measured directly or predicted reliably. While recent studies demonstrated the validity of the surrogate reaction approach for studying fission cross sections for short-lived actinides, its applicability for radiative neutron capture reactions ((n,γ)) is still under investigation. We studied the γ decay of excited 88Y and 90,91Zr nuclei produced by 89Y(p,d), 91Zr(p,d), and 92Zr(p,d) reactions, respectively, in order to infer the 87Y(n,γ) and 89, 90Zr(n,γ) cross sections. The experiments were carried out at the K150 Cyclotron facility at Texas A&M University with a 28.5-MeV proton beam. The reaction deuterons were measured at forward angles of 25-60° with the array of three segmented Micron S2 silicon detectors. The compound nuclei with energies up to a few MeV above the neutron separation thresholds were populated. The coincident γ-rays were measured with the array of five Compton-suppressed HPGe clover detectors.

  2. Evidence of intermediate structure in 12C plus 24Mg system

    Studies of backward resonance structures have been performed for the 12C, 24Mg system at 1800 c.m. Excitation functions were measured using the 24Mg beam of the Saclay F.N. Van de Graaff and by detecting at 00 the 12C recoil nuclei with a QDDD magnetic spectrometer. Havar and/or gold foils were placed in front of the focal plane gas counter in order to stop the 24Mg beam. The target was made of a 50 μg/cm2 carbon layer plus a 10 μg/cm2 gold deposit for beam intensity monitoring. The results are presented between 11- and 27 MeV c.m. for the g.s. 0+, first 2+ state of 24Mg and first 2+ state of 12C. The step in energy is 133 keV c.m. The coulomb barrier is about 12 MeV. A certain correlation can be observed between the elastic and inelastic excitation functions. The coherence width calculated is about 600 keV for a average interval of 4.1 MeV c.m. The normalized cross-correlation coefficients are respectively -0.33 and -0.37 for correlation between g.s. and first 2+ of 24Mg and first 2+ of 12C. The cross-correlation cofficient between the two 2+ states is 0.01

  3. Excitation of giant resonances in {sup 208}Pb, {sup 120}Sn, {sup 90}Zr and {sup 60}Ni by 84 Mev/nucleon {sup 17}O ions

    Alamanos, N.; Liguori-Neto, R.; Roussel-Chomaz, P.; Rochais, L.; Auger, F.; Fernandez, B.; Gillibert, A.; Lacey, R. [CEA Centre d`Etudes de Saclay, 91 - Gif-sur-Yvette (FR). Direction des Sciences de la Matiere; Blumenfeld, Y.; Frascaria, N.; Garon, J.P.; Roynette, J.C.; Scarpacci, J.A.; Suomijarvi, T. [Paris-11 Univ., 91 - Orsay (FR). Inst. de Physique Nucleaire; Barrette, J.; Mark, S.K.; Turcotte, R. [McGill Univ., Montreal, PQ (CA). Foster Radiation Lab.; Van der Woude, A.; Van der Berg, A.M. [Rijksuniversiteit Groningen (NL). Kernfysisch Versneller Inst.

    1991-12-31

    Elastic and inelastic scattering of 1435 MeV {sup 17}O ions on {sup 208}Pb, {sup 120}Sn, {sup 90}Zr and {sup 60}Ni have been measured. Parameters of the isoscalar giant monopole and quadrupole resonances are obtained. The quadrupole resonance exhausts {approx} 60% of the energy weighted sum rule while the observed monopole resonance corresponds to more than 100% of the sum rule.

  4. Relevance of single-particle and collective excitations in zirconium isotopes populated by neutron transfer reactions in the {sup 90}Zr+{sup 208}Pb system

    Pajtler, M. Varga, E-mail: maja.varga@fizika.unios.hr [Department of Physics, University of Osijek, Trg Ljudevita Gaja 6, 31000 Osijek (Croatia); Szilner, S.; Malenica, D. Jelavić; Mijatović, T.; Soić, N. [Ruer Bošković Institute, HR-10001, Zagreb (Croatia); Corradi, L.; Angelis, G. de; Fioretto, E.; Montanari, D.; Stefanini, A. M.; Valiente-Dobón, J. J. [Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Legnaro, I-35020 Legnaro (Italy); Gadea, A. [IFIC, CSIC-Universidad de Valencia, E-46071 Valencia (Spain); Haas, F. [Institut Pluridisciplinaire Hubert Curien, CNRS-IN2P3 and Université de Strasbourg, F-67037 Strasbourg (France); Lunardi, S.; Mengoni, D.; Montagnoli, G.; Recchia, F.; Scarlassara, F. [Dipartimento di Fisica, Universitá di Padova, and Istituto Nazionale di Fisica Nucleare, I-35131 Padova (Italy); Märginean, N. [Horia Hulubei National Institute of Physics and Nuclear Engineering, RO-077125 Bucharest-Magurele (Romania); Pollarolo, G. [Dipartimento di Fisica Teorica, Universitá di Torino,and Istituto Nazionale di Fisica Nucleare, I-10125 Torino (Italy); and others

    2015-10-15

    Multineutron transfer reaction {sup 90}Zr+{sup 208}Pb has been studied at the energy close to the Coulomb barrier energy by using the PRISMA + CLARA set-up. In this fragment-γ coincidence measurement, the selective properties of the reaction mechanism in the population of the specific states have been discussed. Based on the observed γ transitions of neutron transfer channels, namely {sup 89–94}Zr isotopes, their level schemes have been constructed and updated.

  5. Study of the unusual increase in the Curie temperature of the residual amorphous phase in nanocrystalline Fe90Zr7B2Cu1

    Nanocrystalline Fe90Zr7B2Cu1 with ferromagnetic BCC nanocrystals of about 10-20 nm size embedded in a residual amorphous matrix was produced from amorphous precursor by partial crystallization. A significant increase in the Curie temperature of the residual amorphous phase (TC) as compared to that of the amorphous precursor was found by combined bulk magnetic and Moessbauer measurements. The unusual increase of TC for alloys with different nanocrystalline fractions correlates with the quantity of the BCC phase

  6. $^{24}$Mg($p$, $\\alpha$)$^{21}$Na reaction study for spectroscopy of $^{21}$Na

    Cha, S M; Kim, A; Lee, E J; Ahn, S; Bardayan, D W; Chipps, K A; Cizewski, J A; Howard, M E; Manning, B; O'Malley, P D; Ratkiewicz, A; Strauss, S; Kozub, R L; Matos, M; Pain, S D; Pittman, S T; Smith, M S; Peters, W A

    2015-01-01

    The $^{24}$Mg($p$, $\\alpha$)$^{21}$Na reaction was measured at the Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory in order to better constrain spins and parities of energy levels in $^{21}$Na for the astrophysically important $^{17}$F($\\alpha, p$)$^{20}$Ne reaction rate calculation. 31 MeV proton beams from the 25-MV tandem accelerator and enriched $^{24}$Mg solid targets were used. Recoiling $^{4}$He particles from the $^{24}$Mg($p$, $\\alpha$)$^{21}$Na reaction were detected by a highly segmented silicon detector array which measured the yields of $^{4}$He particles over a range of angles simultaneously. A new level at 6661 $\\pm$ 5 keV was observed in the present work. The extracted angular distributions for the first four levels of $^{21}$Na and Distorted Wave Born Approximation (DWBA) calculations were compared to verify and extract angular momentum transfer.

  7. Experimental constraints on the γ-ray strength function in 90Zr using partial cross sections of the Y89(p,γZr90 reaction

    L. Netterdon

    2015-05-01

    Full Text Available Partial cross sections of the Y89(p,γZr90 reaction have been measured to investigate the γ-ray strength function in the neutron–magic nucleus 90Zr. For five proton energies between Ep=3.65 MeV and Ep=4.70 MeV, partial cross sections for the population of seven discrete states in 90Zr have been determined by means of in-beam γ-ray spectroscopy. Since these γ-ray transitions are dominantly of E1 character, the present measurement allows an access to the low-lying dipole strength in 90Zr. A γ-ray strength function based on the experimental data could be extracted, which is used to describe the total and partial cross sections of this reaction by Hauser–Feshbach calculations successfully. Significant differences with respect to previously measured strength functions from photoabsorption data point towards deviations from the Brink–Axel hypothesis relating the photo-excitation and de-excitation strength functions.

  8. Emission of β+ Particles Via Internal Pair Production in the 0+ – 0+ Transition of 90Zr: Historical Background and Current Applications in Nuclear Medicine Imaging

    Marco D'Arienzo

    2013-03-01

    Full Text Available 90Y is traditionally considered as a pure β– emitter. However, the decay of this radionuclide has a minor branch to the 0+ first excited state of 90Zr at 1.76 MeV, that is followed by a β+/β– emission. This internal pair production has been largely studied in the past because it is generated by a rare electric monopole transition (E0 between the states 0+/0+ of 90Zr. The positronic emission has been recently exploited for nuclear medicine applications, i.e. positron emission tomography (PET acquisitions of 90Y-labelled radiopharmaceuticals, widely used as therapeutic agents in internal radiation therapy. To date, this topic is gaining increasing interest in the radiation dosimetry community, as the possibility of detecting β+ emissions from 90Y by PET scanners may pave the way for an accurate patient-specific dosimetry. This could lead to an explosion in scientific production in this field. In the present paper the historical background behind the study of the internal pair production of the 0+/0+ transition of 90Zr is presented along with most up to date measured branch ratio values. An overview of most recent studies that exploit β+ particles emitted from 90Y for PET acquisitions is also provided.

  9. Fission fragment angular distribution in 24Mg induced reactions on 192Os and 197Au

    Angular distributions of fission fragments have been measured in 24Mg + 192Os and 24Mg + 197Au reactions at Elab = 128 MeV which is close to entrance channel Coulomb barrier. Experimental angular anisotropies were in reasonably good agreement with those calculated using the statistical theory. Analysis of the angular distribution data of the present study and of our earlier measurement in 19F + 197Au reaction has shown that contribution from non-compound nucleus fission in these systems is not significant. (author)

  10. Entrance channel dependence of back angle yields: orbiting in 24Mg+16O reaction

    The back-angle yields of the oxygen and carbon particles from the 24Mg+16O reaction have been measured at E/sub Lab/(24Mg) = 79.5 MeV by using reverse kinematics. Comparison with data for the 28Si+12C reaction forming the same compound nucleus at the same excitation energy and with very similar spin distribution, demonstrates a strong entrance channel effect which is favoring the break-up into the entrance channel with large excitation energy. This result qualitatively supports the picture of the formation of a long-lived orbiting complex whose structure and decay are dependent on the entrance channel. The compound nucleus contribution has been inferred to be less than 15% of the measured oxygen cross-section. 9 references

  11. Reaction mechanism for the symmetric breakup of 24Mg following an interaction with 12C

    Data on the yield of the symmetric breakup of 24Mg as a function of beam energy are presented and compared with detailed calculations of the energy dependence. The 24Mg states seen in symmetric breakup agree with previously observed breakup states having spin and parities Jπ=4+,(6+),8+. The data allow the variations of yield for indivual states to be judged, as the beam energy is varied. The variation in the yield of the 4+ states is compared in detail with calculations assuming several possible compound nuclear or direct reaction mechanisms. It is concluded that a massive (12C) transfer or a simple statistical compound process are unlikely mechanisms, but that each of several other mechanisms is consistent with the data. ((orig.))

  12. Excitation of giant resonances in [sup 208]Pb, [sup 120]Sn, [sup 90]Zr and [sup 60]Ni by 84 MeV/nucleon [sup 17]O ions

    Liguori Neto, R. (DAPNIA/SPhN, Centre d' Etudes Nucleaires de Saclay, 91 - Gif-sur-Yvette (France)); Roussel-Chomaz, P. (DAPNIA/SPhN, Centre d' Etudes Nucleaires de Saclay, 91 - Gif-sur-Yvette (France)); Rochais, L. (DAPNIA/SPhN, Centre d' Etudes Nucleaires de Saclay, 91 - Gif-sur-Yvette (France)); Alamanos, N. (DAPNIA/SPhN, Centre d' Etudes Nucleaires de Saclay, 91 - Gif-sur-Yvette (France)); Auger, F. (DAPNIA/SPhN, Centre d' Etudes Nucleaires de Saclay, 91 - Gif-sur-Yvette (France)); Fernandez, B. (DAPNIA/SPhN, Centre d' Etudes Nucleaires de Saclay, 91 - Gif-sur-Yvette (France)); Gastebois, J. (DAPNIA/SPhN, Centre d' Etudes Nucleaires de Saclay, 91 - Gif-sur-Yvette (France)); Gillibert, A. (DAPNIA/SPhN, Centre d' Etudes Nucleaires de Saclay, 91 - Gif-sur-Yvette (France)); Lacey, R. (DAPNIA/SPhN, Centre d' Etudes Nucleaires de Saclay, 91 - Gif-sur-Yvette (France)); Miczaika, A. (DAPNIA/SPhN, Centre d' Etudes Nucleaires de Saclay, 91 - Gif-sur-Yvette (France)); Pierroutsakou, D. (DAPNI

    1993-07-19

    Elastic and inelastic scattering of 1435 MeV [sup 17]O ions on [sup 208]Pb, [sup 120]Sn, [sup 90]Zr and [sup 60]Ni have been measured. Hindrance in the excitation of the first 3[sup -] states is observed. Parameters of the isoscalar giant monopole and quadrupole resonances are obtained. The quadrupole resonance exhausts [approx]55% of the energy-weighted sum rule while the observed monopole resonance corresponds to more than 100% of the sum rule. Strength is also observed at high excitation energy in all targets. (orig.)

  13. Selective properties of neutron transfer reactions in the 90Zr + 208Pb system for the population of excited states in zirconium isotopes

    Nuclei produced via multineutron transfer channels have been studied in 90Zr + 208Pb close to the Coulomb barrier energy in a fragment-γ coincident measurement employing the PRISMA magnetic spectrometer coupled to the CLARA γ-array. The selective properties of the reaction mechanism have been discussed in terms of states and their strength excited in the neutron transfer channels leading to 89–94Zr isotopes. A strong population of yrast states, with energies up to ∼7.5 MeV has been observed

  14. Selective properties of neutron transfer reactions in the {sup 90}Zr + {sup 208}Pb system for the population of excited states in zirconium isotopes

    Varga Pajtler, M., E-mail: mvarga@fizika.unios.hr [Department of Physics, University of Osijek, HR-31000 Osijek (Croatia); Szilner, S. [Rudjer Bošković Institute, HR-10001 Zagreb (Croatia); Corradi, L.; Angelis, G. de; Fioretto, E. [Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Legnaro, I-35020 Legnaro (Italy); Gadea, A. [IFIC, CSIC-Universidad de Valencia, E-46071 Valencia (Spain); Haas, F. [Institut Pluridisciplinaire Hubert Curien, CNRS-IN2P3 and Université de Strasbourg, F-67037 Strasbourg (France); Lunardi, S. [Dipartimento di Fisica, Universitá di Padova, and Istituto Nazionale di Fisica Nucleare, I-35131 Padova (Italy); Jelavić Malenica, D. [Rudjer Bošković Institute, HR-10001 Zagreb (Croatia); Mărginean, N. [Horia Hulubei National Institute of Physics and Nuclear Engineering, RO-077125 Bucharest-Magurele (Romania); Mengoni, D. [Dipartimento di Fisica, Universitá di Padova, and Istituto Nazionale di Fisica Nucleare, I-35131 Padova (Italy); Mijatović, T. [Rudjer Bošković Institute, HR-10001 Zagreb (Croatia); Montagnoli, G. [Dipartimento di Fisica, Universitá di Padova, and Istituto Nazionale di Fisica Nucleare, I-35131 Padova (Italy); Montanari, D. [Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Legnaro, I-35020 Legnaro (Italy); Pollarolo, G. [Dipartimento di Fisica Teorica, Universitá di Torino, and Istituto Nazionale di Fisica Nucleare, I-10125 Torino (Italy); and others

    2015-09-15

    Nuclei produced via multineutron transfer channels have been studied in {sup 90}Zr + {sup 208}Pb close to the Coulomb barrier energy in a fragment-γ coincident measurement employing the PRISMA magnetic spectrometer coupled to the CLARA γ-array. The selective properties of the reaction mechanism have been discussed in terms of states and their strength excited in the neutron transfer channels leading to {sup 89–94}Zr isotopes. A strong population of yrast states, with energies up to ∼7.5 MeV has been observed.

  15. Neutron and proton optical potentials for 12C, 16O, 27Al, 56Fe, 90Zr and 208Pb up to 250 MeV

    In order to perform nuclear data evaluation without unphysical discontinuities, optical models should cover the whole mass and energy range of interest continuously. In this work, the best set of optical model parameters were obtained with energy dependent potential forms which incorporate effects of dispersion relationship for neutron and proton up to 250 MeV on 12C, 16O, 27Al, 56Fe, 90Zr and 208Pb. Applicability of adopting an identical geometrical factor for the real volume, imaginary volume and imaginary surface potentials has been investigated as well in the process of parameter search. (author)

  16. Configuration analysis of the 6.0 MeV 4+ state in 24Mg

    The configuration of the 6.0 MeV 4+ state in 24Mg has been investigated using the inelastic electron scattering form factor for this level. It is shown that 1s-0d shell cannot describe the observed form factor successfully. The amount of Og shell admixture in this transition is estimated. Saxon-Woods wavefunctions and phase-shift analysis have been used. (Auth.)

  17. Electron scattering from 20Ne and 24Mg in a microscopic boson model

    It is shown that a mean-field approximation applied to the microscopically derived boson Hamiltonian yields a reasonable description of the form factors for both elastic and inelastic electron scattering from some sd-shell nuclei (20Ne, 24Mg). The results agree well with experimental data for the 0+ → 0+ and 0+ → 2+ transitions but much less so for the 0+ → 4+ transitions. Possible sources of the observed discrepancies are suggested

  18. Study and realization of heavy ion detectors. Application to the reaction 12C+24Mg

    The present study deals with elastic and inelastic scattering of 24 to 44 MeV center of mass 24Mg ions by 12C. The Strasbourg Q3D magnetic spectrograph has been used to measure the 1800 c.m. scattering cross-sections in detecting the corresponding recoiling ions at THETAsub(Lab) = 00. Statistical fluctuations are probably present. The 1,5 m long position sensitive focal plan hybride counter is described

  19. Resonances-Excitation Calculation Studies Investigation of Δ(3, 3) in Ground State of 90Zr Cold Finite Heavy Nucleus at Equilibrium and Under Large Compression

    A non-relativistic microscopic mean field theory of finite nuclei is investigated where the nucleus is described as a collection of nucleons and delta resonances. The ground state properties of 90Zr nucleus have been investigated at equilibrium and large amplitude compression using a realistic effective baryon-baryon Hamiltonian based on Reid Soft Core (RSC) potential. The sensitivity of the ground state properties is studied, such as binding energy, nuclear radius, radial density distribution, and single particle energies to the degree of compression. It is found that the most of increasing in the nuclear energy generated under compression is used to create the massive Δ particles. For 90Zr nucleus under compression at 2.5 times density of the normal nuclear density, the excited nucleons to Δ's are increased sharply up to 14% of the total number of constituents. This result is consistent with the values extracted from relativistic heavy-ion collisions. The single particle energy levels are calculated and their behaviors under compression are examined too. A good agreement between results with effective Hamiltonian and the phenomenological shell model for the low lying single-particle spectra is obtained. A considerable reduction in compressibility for the nucleus, and softening of the equation of state with the inclusion of the Δ's in the nuclear dynamics are suggested by the results. (nuclear physics)

  20. Experimental study of the fast neutron scattering from 24Mg, 28Si and 32S

    Differential cross section measurements for neutron scattering from 24Mg, 28Si and 32S at 9.76 and 14.83 MeV incident neutron energies have been undertaken. The experimental technique is based on the time-of-flight method with a pulsed neutron beam. Scattered neutrons have been detected by a spectrometer composed of five detectors. Elastic and inelastic scattering cross sections for levels of up to 6 MeV excitation energy have been obtained for the angular range from 15 to 1600 in 50 steps. These measurements will be used in a coupled-channel analysis to extract potential and deformation parameters

  1. Fourier-transform microwave spectroscopy of 24Mg 35Cl generated by laser ablation

    Ohshima, Yasuhiro; Endo, Yasuki

    1993-10-01

    The rotational spectrum of 24Mg 35Cl in its X 2Σ + (ν=0 and 1 ) state has been observed in the 14 GHz region by using a Fourier- transform microwave spectrometer combined with a laser-ablation source. The radical was produced by the reaction of atomic Mg vaporized by 532 nm laser light with Cl 2 diluted in Ar. The present observation of the lowest N transition by a high-resolving power instrument has provided accurate hyperfine coupling constants associated with the 35Cl nucleus of this molecule.

  2. Study of the 28Si(16O,20Ne)24Mg reaction

    In this work, measurements of elastic and inelastic angular distributions in the system 16O+ 20Si and in the alpha transfer reactions 20Si(16O,20Ne)24Mg were made in the angular range of 200 0 and the transfer reaction 20Si(16O,12C)32S in the angular range 160 0 at the energy of Ecm = 31.57 MeV. Optical potential parameters and β2 deformation parameters as well as spectroscopic factors were determined for the alpha transfer reactions. (A.C.A.S.)

  3. Clustering aspects in N = Z nucleus 24Mg studied by antisymmetized molecular dynamics

    Cluster structure of highly excited states of 24Mg has been investigated by the antisymmetrized molecular dynamics. Imposing the constraints on the expectation values of harmonic oscillator quanta, α+20Ne, 12C+12C and 6α cluster wave functions were generated without any a priori assumption. The isoscalar monopole excitation function is also calculated and reasonably agrees with the observation. It is found that α+20Ne, 12C+12C and 6α clusters appear as the prominent peaks in the strength function

  4. Study of the elastic scattering of {sup 32}S by {sup 24}Mg at low energies

    Hassanain, Mahmoud A., E-mail: mho1959@yahoo.com [Department of Physics, King Khalid University, Abha (Saudi Arabia); Ibraheem, Awad A. [Department of Physics, King Khalid University Physics Department, Al-Azhar University (Egypt)

    2015-12-15

    The elastic scattering angular distribution of {sup 32}S on {sup 24}Mg at energies ranging from 65 to 110 MeV has been analyzed in the framework of the double folding (DF) model, using different effective nucleon-nucleon (NN) interactions based on the M3Y-Reid interaction. The Pauli correlation, zero-range, and finite-range exchange parts of the NN interactions are considered in the folding procedure to treat the single nucleon knock-on exchange term (SNKE) in the optical model. Successful reproduction of the data has been obtained with all the potentials considered in the present study. It is clear that the effect of Pauli correlation increases as the energy increases. Our calculations are insensitive to the strength of the imaginary potential used in the fit of the experimental data. We find also that the threshold anomaly is less pronounced in the {sup 32}S + {sup 24}Mg system. Our reaction cross sections are compared with the data, and the consistency between the real and imaginary volume integrals are checked by the dispersion relation. (author)

  5. Calculation of neutron cross sections for 90Zr, 208Pb and 209Bi in the energy range of 0.5-25 MeV by using the optical model potentials

    Neutron total cross sections and differential elastic scattering cross sections for the nuclides 90Zr, 208Pb and 209Bi were calculated using different global spherical optical potential (SOP) parameter sets at neutron energies from 0.5-25 MeV. Calculated cross sections for the corresponding nuclides were compared with their experimental data obtained by the EXFOR file to select the best fit parameter sets. It is found that the parameter sets of Ferer Rapaport for 90Zr and Bechetti and Greenless for 208Pb and 209Bi are the best fitted set to obtain the experimental data of total cross sections and angular distributions of these nuclides. (author)

  6. An interpretation of gross structures in the energy spectra of 12C (16O,α)24Mg reaction

    Recent studies of the 12C(16O,α)24Mg reaction at E(16O) = 145 Mev have revealed the existence of several broad states with E sub(X)(24Mg) = 20 to 60 MeV. The energies of these states have been taken as evidence that they are members of the 12C + 12C molecular band J sup(π) = (10+) through J sup(π) = (18+). Subsequent investigation of the properties of these states, however, has failed to reveal the expected partial width for 24Mg* → 12C + 12C. It is shown that these states can be interpreted as an extension of the 24Mg Yrast sequence which is populated by the well understood high spin selectivity of α particle evaporation from a 28Si compound nucleus. (Author)

  7. Splitting of ISGMR strength in the light-mass nucleus $^{24}$Mg due to ground-state deformation

    Gupta, Y K; Matta, J T; Patel, D; Peach, T; Hoffman, J; Yoshida, K; Itoh, M; Fujiwara, M; Hara, K; Hashimoto, H; Nakanishi, K; Yosoi, M; Sakaguchi, H; Terashima, S; Kishi, S; Murakami, T; Uchida, M; Yasuda, Y; Akimune, H; Kawabata, T; Harakeh, M N

    2015-01-01

    The isoscalar giant monopole resonance (ISGMR) strength distribution in $^{24}$Mg has been determined from background-free inelastic scattering of 386-MeV $\\alpha$ particles at extreme forward angles, including 0$^{\\circ}$. The ISGMR strength distribution has been observed for the first time to have a two-peak structure in a light-mass nucleus. This splitting of ISGMR strength is explained well by microscopic theory in terms of the prolate deformation of the ground state of $^{24}$Mg.

  8. An Analysis of the $^{12}$C+$^{24}$Mg Reaction Using A New Coupling Potential

    Boztosun, I

    2001-01-01

    We introduce a new coupling potential to explain the experimental data for the $^{12}$C+$^{24}$Mg system at numerous energies in the laboratory system from 16.0 MeV to 24.0 MeV. This new coupled-channels based approach involves replacing the usual first derivative coupling potential by a new, second-derivative coupling potential. This paper first shows and discusses the limitation of the standard coupled-channels theory in the case where one of the nuclei in the reaction is strongly deformed. Then, this new approach is shown to improve consistently the agreement with the experimental data and has made major improvement on all the previous coupled-channels calculations for this system.

  9. Nuclear transparency and the onset of strong absorption regime in the 12C+24Mg system

    Lichtenthäler, R.; Lépine-Szily, A.; Hussein, M. S.

    1999-10-01

    The elastic scattering of 12C+24Mg has been studied by means of a phase-shift analysis of 21 angular distributions ranging from Elab=16 MeV up to Elab=40 MeV. A tridimensional plot of the reflection coefficient of the S matrix as a function of the angular momentum and energy shows a well-defined region of energy, which separates two regimes: strong absorption for higher energies and the so-called ``anomalous transparency regime,'' recently observed in this system at low energies. The Argand diagrams of the S matrix in angular momentum space also present very contrasting behaviors in the two regions with very rapidly varying phases in the low energy region, which we associate with a parity dependent term in the S matrix directly related to significant coupling to the elastic transfer of a 12C nucleus.

  10. Nuclear transparency and the onset of strong absorption regime in the $^{12}C + ^{24}Mg$ system

    Lichtenthäler, R; Hussein, M S

    1999-01-01

    The elastic scattering of 12C+24Mg has been studied by means of a phase-shift analysis of 21 angular distributions ranging from Elab=16MeV up to Elab=40MeV. A tri-dimensional plot of the reflection coefficient of the S-matrix as a function of the angular momentum and the energy shows a well defined region of energy which separates two regimes: strong absorption for higher energies and the so called "anomalous transparency regime", recently observed in this system at low energies. The Argand diagrams of the S-matrix in angular momentum space also present very contrasting behaviours in the two regions with very rapidly varying phases in the low energy region, which we associate with a parity dependent term in the S-matrix directly related to significant coupling to the elastic transfer of a 12C nucleus.

  11. Cyclotron production of high purity 44m,44Sc with deuterons from 44CaCO3 targets

    Introduction: Due to its longer half-life, 44Sc (T1/2 = 3.97 h) as a positron emitter can be an interesting alternative to 68Ga (T1/2 = 67.71 min). It has been already proposed as a PET radionuclide for scouting bone disease and is already available as a 44Ti/44Sc generator. 44Sc has an isomeric state, 44mSc (T1/2 = 58.6 h), which can be co-produced with 44Sc and that has been proved to be considered as an in-vivo PET generator 44mSc/44Sc. This work presents the production route of 44mSc/44Sc generator from 44Ca(d,2n), its extraction/purification process and the evaluation of its performances. Methods: Irradiation was performed in a low activity target station using a deuteron beam of 16 MeV, which favors the number of 44mSc atoms produced simultaneously to 44Sc. Typical irradiation conditions were 60 min at 0.2 μA producing 44 MBq of 44Sc with a 44Sc/44mSc activity ratio of 50 at end of irradiation. Separations of the radionuclides were performed by means of cation exchange chromatography using a DGA® resin (Triskem). Then, the developed process was applied with bigger targets, and could be used for preclinical studies. Results: The extraction/purification process leads to a radionucleidic purity higher than 99.99% (43Sc, 46Sc, 48Sc < DL). 44mSc/44Sc labeling towards DOTA moiety was performed in order to get an evaluation of the specific activities that could be reached with regard to all metallic impurities from the resulting source. Reaction parameters of radiolabeling were optimized, reaching yields over 95%, and leading to a specific activity of about 10–20 MBq/nmol for DOTA. A recycling process for the enriched 44Ca target was developed and optimized. Conclusion: The quality of the final batch with regard to radionucleidic purity, specific activity and metal impurities allowed a right away use for further radiopharmaceutical evaluation. This radionucleidic pair of 44mSc/44Sc offers a quite interesting PET radionuclide for being further evaluated as an in

  12. Study of the interaction potential between 12 C and 24 Mg: an example of anomalous transparency

    Complete angular distributions of the 12 C + 24 Mg elastic scattering were measured at ECM = 10.67 and 11.33 MeV, and from ECM = 12.0 to 16.0 MeV, using a 12 C beam produced at Pelletron Accelerator. This energy range is close to the Coulomb barrier of tue system, which is 12.53 MeV. Surprisingly all the angular distributions show strong oscillations even at energies bellow the Coulomb barrier. The angular distributions were fitted by optical model calculations and we determined the shallowest real potential, without continuous ambiguity. The main features of this potential are: very transparent even at the nuclear interior and strong dependence with energy of the real imaginary depths Vo and Wo. At five energies the inelastic scattering data were also analysed and well fitted by coupled-channels calculations. The optical potentials of all channels present the threshold anomaly and are well reproduced by dispersion relation calculations applied to the volume integrals of the optical potentials. (author). 50 refs., 41 figs., 12 tabs

  13. The intermediate energy elastic scattering of protons by α-cluster 20Ne and 24Mg nuclei

    The multiple diffraction scattering theory and the α-cluster model with dispersion have been applied for calculations of the observables for the elastic scattering of intermediate energy protons by 20Ne and 24Mg nuclei. The target nuclei are considered as composed of the core (16O nucleus) and additional α-clusters (one α-cluster for 20Ne nucleus and a dumb-bell α-cluster configuration for 24Mg nucleus). Taking into account the α-cluster configuration of the core, it was supposed that the additional α-cluster or center of mass of the dumb-bell are arranged with the most probability inside or outside of the core. The calculated observables for the elastic p–20Ne and p–24Mg scattering are in agreement with the existing experimental data. The influence of the deformed core contribution on the behavior of the calculated observables also is tested. (author)

  14. Ion microscopic imaging of calcium transport in the intestinal tissue of vitamin D-deficient and vitamin D-replete chickens: A 44Ca stable isotope study

    The intestinal absorption of calcium includes at least three definable steps; transfer across the microvillar membrane, movement through the cytosolic compartment, and energy-dependent extrusion into the lamina propria, Tracing the movement of calcium through the epithelium has been hampered by lack of suitable techniques and, in this study, advantage was taken of ion microscopy in conjunction with cryosectioning and use of the stable isotope 44Ca to visualize calcium in transit during the absorptive process. The effect of vitamin D, required for optimal calcium absorption, was investigated. Twenty millimolar 44Ca was injected into the duodenal lumen in situ of vitamin D-deficient and vitamin D-replete chickens. At 2.5, 5.0, and 20.0 min after injection, duodenal tissue was obtained and processed for ion microscopic imaging. At 2.5 min. 44Ca was seen to be concentrated in the region subjacent to the microvillar membrane in tissue from both groups. At 5.0 and 20.0 min, a similar pattern of localization was evident in D-deficient tissues. In D-replete tissues, the distribution of 44Ca became more homogenous, indicating that vitamin D increased the rate of transfer of Ca2+ from the apical to the basolateral membrane, a function previously ascribed to the vitamin D-induced calcium-binding protein (28-kDa calbindin-D). Quantitative aspects of the calcium absorptive process were determined in parallel experiments with the radionuclide 47Ca. Complementary information on the localization of the naturally occurring isotopes of calcium (40Ca) and potassium (39K) is also described

  15. Cross section determination of threshold like (n,p), (n,α) and (n,2n) reactions with 14 MeV neutrons for the 50Ti, 68Zn and 90Zr nuclides

    Activation cross-sections at (14,4 + - 0,3) MeV neutron energy have been measured by means of conventional and cyclic activation techniques, utilizing an intense sealed tube neutron generator of cylindrical ion-acceleration structure (KORONA). The reactions investigated and the corresponding cross-sections (in mb) are: 50Ti(n,p) 50Sc(14,3 + - 2,1); 68Zn(n,p) sup(68g) Cu (5,0 + - 1); 68Zn(n,p) sup(68m) Cu (3,6 + - 0,6); 68Zn (n,α) 65Ni (10,3 + - 1,8); 90Zr (n,p) sup(90m) Y (9,8 +m - 1,7); 90Zr (n,α) sup(87m) Sr (3,2 + - 0,5); 90Zr (n,2n) sup(89m)Zr (75 + - 12). The neutron flux and the mean energy of the neutrons from the KORONA were also determined through the monitor reactions 27Al (n,A)24Na, 90Zr(n,2n)89Zr and 93Nb(n,2n) sup(92m) Nb. For comparison with the experimentally obtained results, the hitherto known cross-section data from the literature were careflly compiled, too, in this work. In the case of the 68Zn(n,p) sup(68g) Cu reaction, a special formulation was developed to calculate its cross-section, taking into consideration the most important fact that all the excited levels of 68Zn arising from the β- decay of sup(68g) Cu are also fed by the β- activity decay of sup(68m) Cu and by the isomeric transitions and internal conversions of this metastable state. (Author)

  16. Production of neutral pions below the nucleon-nucleon threshold in the reactions 24Mg(16O,π0)X and 24Mg(4He,π0)X

    In the present thesis the production of neutral pions in the reaction 24Mg(16O,π0)X at 24 and 33 MeV/u as well as in the reaction 24Mg(4He,π0)X at a projectile energy of 43 MeV/u was studied by means of a lead-glass Cherenkov detector. The measured energy spectra can be well described by a parametrization by means of 1/E e sup(- E/E0) analogously to the bremsstrahlung model. The decrease parameters extracted from this indicate a stopping time in the order of magnitude of 10-24s, which confirms the assumption that the pions are produced in the early phase of the reaction before the onset of the equilibration of the fused system. (orig./HSI)

  17. Back-angle anomaly and coupling between seven reaction channels of 12C+24Mg using algebraic scattering theory

    We measured six fairly complete angular distributions of elastic, inelastic and α-transfer reactions of the 12C+24Mg system ar Ecm = 25.2 MeV. We performed coupled channels calculations using the Algebraic Scattering Theory with nuclear algebraic potential derived from nuclear phase shifts and using available structure informations for the inelastic coupling strengths. The back angle rise in the elastic cross section is fully explained by the couplings between elastic and transfer channels. (author)

  18. A comparison of spectroscopic models of low excitation 2+ states in 24Mg and 28Si using inelastic proton scattering

    Distorted Wave approximation analyses of the inelastic scattering of 49.5 MeV protons from 24Mg and 28Si are used to compare 2+ transition densities that were obtained from a standard shell model, deformed potential models and an SU(3) model of the low excitation spectroscopy of these nuclei. Analyzing power predictions do not reproduce the data adequately; the discrepancies indicating a deficiency in the transition mechanism prescription

  19. Characteristics of charged projectile fragments from 24Mg-emulsion interactions at 4.5 A GeV/c

    A total sample of 1719 inelastic interactions of 24Mg in emulsion at 4.5 A GeV/c has been used to study the characteristics of projectile fragments. The multiplicity and angular distributions of projectile fragments in interactions with different target components have been investigated. The projected angular distributions of fragments exhibit features of limiting fragmentation. These distributions are consistent with quantum-mechanical calculations using the Sudden approximation and shell-model functions

  20. Spin polarization of 23Mg in 24Mg + Au, Cu and Al collisions at 91 A MeV

    Spin polarization of beta-emitting fragment 23Mg(Iπ = 3/2+, Tl/2 = 11.3 s) produced through the projectile fragmentation process in 24Mg + Au, Cu and Al collisions has been observed at 91 A MeV. General trend in the observed momentum dependence of polarization is reproduced well qualitatively by a simple fragmentation model based on the participant-spectator picture, for heavy and light targets. However the polarization behavior differs from this model in terms of zero crossing momentum, which become prominent in the case of Cu target, where the polarization is not monotone function of the fragment momentum

  1. Microscopic foundation of sdgIBM-2 and study of low-lying states of 24Mg

    A microscopic framework of sdIBM-2 is extended to the one of sdgIBM-2. Introducing hexadecupole pairing force, Hamiltonian and E2, E4 operators of the sdgIBM-2 are deduced microscopically. The nucleus 24Mg in the light-mass region is chosen as the first application of such an extended microscopic approach. Based on strong coupling picture, spectrum, reduced E2 transition rates and reduced E4 transition matrix elements are calculated. The calculated results fit experimental results quite well

  2. Equilibrium and pre-equilibrium calculations of cross-sections of (, ) reactions on 89Y, 90Zr and 94Mo targets used for the production of 89Zr, 90Nb and 94Tc positron-emitting radionuclides

    R Baldik; H Aytekin; E Tel

    2013-02-01

    In this study, the pre-equilibrium and equilibrium calculations of cross-sections of 89Y(, ), 90Zr$(p, xn)$ and 94Mo(, ) reactions, which were used for the production of 89Zr, 90Nb and 94Tc positron-emitting radioisotopes, have been investigated. Pre-equilibrium calculations have been performed at different proton incident energies by using the hybrid, geometry-dependent-hybrid and full exciton models. The Weisskopf–Ewing model is used for calculating the equilibrium effects at the same incident energies. The calculated results have been discussed and compared with the experimental results.

  3. Nuclear molecules and their deexcitation channels, case of Cr48 generated by the Mg24 + Mg24 resonant reaction

    This work is dedicated to the study of the resonance (E = 45,7 MeV, Jπ = 36+, Γ = 170 keV) of the Mg24 + Mg24 composite nucleus. The PRISMA fragment spectrometer combined with the CLARA gamma detector have been used to study the deexcitation through inelastic channels of the composite system. It is showed that the resonant flux is mainly observed in the inelastic channels involving the contributions 0+, 2+ and 4+ of the band based on the fundamental state of Mg24. This is in good agreement with the theoretical predictions of the molecular model of Uegaki and Abe. Only 30% of the resonant flux has been observed in the inelastic channels and in the transfer channels. The missing flux has been investigated in the fusion/evaporation deexcitation channels with the GASP gamma multi-detector. A weak resonant effect has been highlighted in some residual nuclei such as Ti45, Ca42 and K39. A link between the prolate di-nucleus Ca48 generated in Mg24 + Mg24 reaction and a Cr48 nucleus that has just undergone a Jacobi transition from oblate to prolate, has been discovered. To explain a part of the missing flux it is suggested that the dipolar giant resonance might feed very deformed nuclei through particle emission

  4. Separation of reaction mechanisms at low energy. Study of the reactions: 27Al(d,p) 28Al, 24Mg(d,p) 25Mg, and 24Mg(d, α) 22Na

    The two sets of angular distributions of (d,p) reactions on Al and Mg, measured between 2 and 6 MeV, have given the possibility to test, in analysing the statistical fluctuations of cross-section, the validity of the separation of their mean values in two parts, one 'direct', another given by the statistical mechanism. With the same method of analysis we have studied excitation functions for several alpha groups of the reaction 24Mg(d, α) 22Na and given an evidence for an intermediate structure for the alpha channel leading to the 3. excited state of 22Na. The angular distribution of the wide resonance at 15.9 MeV in 26Al has been obtained. (author)

  5. Nuclear molecules and their deexcitation channels, case of Cr{sup 48} generated by the Mg{sup 24} + Mg{sup 24} resonant reaction; Molecules nucleaires et leurs modes de desexcitation: le cas du {sup 48}Cr et de la reaction resonante {sup 24}Mg + {sup 24}Mg

    Salsac, M.D

    2006-12-15

    This work is dedicated to the study of the resonance (E = 45,7 MeV, J{sup {pi}} = 36{sup +}, {gamma} = 170 keV) of the Mg{sup 24} + Mg{sup 24} composite nucleus. The PRISMA fragment spectrometer combined with the CLARA gamma detector have been used to study the deexcitation through inelastic channels of the composite system. It is showed that the resonant flux is mainly observed in the inelastic channels involving the contributions 0{sup +}, 2{sup +} and 4{sup +} of the band based on the fundamental state of Mg{sup 24}. This is in good agreement with the theoretical predictions of the molecular model of Uegaki and Abe. Only 30% of the resonant flux has been observed in the inelastic channels and in the transfer channels. The missing flux has been investigated in the fusion/evaporation deexcitation channels with the GASP gamma multi-detector. A weak resonant effect has been highlighted in some residual nuclei such as Ti{sup 45}, Ca{sup 42} and K{sup 39}. A link between the prolate di-nucleus Ca{sup 48} generated in Mg{sup 24} + Mg{sup 24} reaction and a Cr{sup 48} nucleus that has just undergone a Jacobi transition from oblate to prolate, has been discovered. To explain a part of the missing flux it is suggested that the dipolar giant resonance might feed very deformed nuclei through particle emission.

  6. Separation of reaction mechanisms at low energy. Study of the reactions: {sup 27}Al(d,p) {sup 28}Al, {sup 24}Mg(d,p) {sup 25}Mg, and {sup 24}Mg(d, {alpha}) {sup 22}Na; Sur la separation des mecanismes de reaction a basse energie. Etude des reactions: {sup 27}Al(d,p) {sup 28}Al, {sup 24}Mg(d,p) {sup 25}Mg, et {sup 24}Mg(d, {alpha}) {sup 22}Na

    Mermaz, M. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1966-06-01

    The two sets of angular distributions of (d,p) reactions on Al and Mg, measured between 2 and 6 MeV, have given the possibility to test, in analysing the statistical fluctuations of cross-section, the validity of the separation of their mean values in two parts, one 'direct', another given by the statistical mechanism. With the same method of analysis we have studied excitation functions for several alpha groups of the reaction {sup 24}Mg(d, {alpha}) {sup 22}Na and given an evidence for an intermediate structure for the alpha channel leading to the 3. excited state of {sup 22}Na. The angular distribution of the wide resonance at 15.9 MeV in {sup 26}Al has been obtained. (author) [French] Les deux ensembles de distributions angulaires des reactions (d,p) sur Al et Mg, mesures entre 2 et 6 MeV, nous ont permis, en analysant les fluctuations statistiques de sections efficaces, de verifier la possibilite de la separation de leurs valeurs moyennes en deux composantes: l'une 'directe', l'autre due au mecanisme statistique. Avec la meme methode d'analyse nous avons etudie les fonctions d'excitation des premiers groupes alpha de la reaction {sup 24}Mg(d,{alpha}) {sup 22}Na et mis en evidence une structure intermediaire pour la voie de reaction aboutissant au 3eme niveau de {sup 22}Na. Nous avons obtenu la distribution angulaire de la resonance large situee a une energie d'excitation de 15,9 MeV dans {sup 26}Al. (auteur)

  7. Detailed microscopic calculation of stellar electron and positron capture rates on 24Mg for O+Ne+Mg core simulations

    Few white dwarfs, located in binary systems, may acquire sufficiently high mass accretion rates resulting in the burning of carbon and oxygen under nondegenerate conditions forming a O+Ne+Mg core. These O+Ne+Mg cores are gravitationally less bound than more massive progenitor stars and can release more energy due to the nuclear burning. They are also amongst the probable candidates for low entropy r-process sites. Recent observations of subluminous Type II-P supernovae (e.g., 2005cs, 2003gd, 1999br, 1997D) were able to rekindle the interest in 8 - 10 M which develop O+Ne+Mg cores. Microscopic calculations of capture rates on 24Mg, which may contribute significantly to the collapse of O+Ne+Mg cores, using shell model and proton-neutron quasiparticle random phase approximation (pn-QRPA) theory, were performed earlier and comparisons made. Simulators, however, may require these capture rates on a fine scale. For the first time a detailed microscopic calculation of the electron and positron capture rates on 24Mg on an extensive temperature-density scale is presented here. This type of scale is more appropriate for interpolation purposes and of greater utility for simulation codes. The calculations are done using the pn-QRPA theory using a separable interaction. The deformation parameter, believed to be a key parameter in QRPA calculations, is adopted from experimental data to further increase the reliability of the QRPA results. The resulting calculated rates are up to a factor of 14 or more enhanced as compared to shell model rates and may lead to some interesting scenario for core collapse simulators. (author)

  8. Stellar neutrino energy loss rates due to $^{24}$Mg suitable for O+Ne+Mg core simulations

    Nabi, Jameel-Un

    2011-01-01

    Neutrino losses from proto-neutron stars play a pivotal role to decide if these stars would be crushed into black holes or explode as supernovae. Recent observations of subluminous Type II-P supernovae (e.g., 2005cs, 2003gd, 1999br, 1997D) were able to rejuvenate the interest in 8-10 M$_{\\odot}$ stars which develop O+Ne+Mg cores. Simulation results of O+Ne+Mg cores show varying results in converting the collapse into an explosion. The neutrino energy loss rates are important input parameters in core collapse simulations. Proton-neutron quasi-particle random phase approximation (pn-QRPA) theory has been used for calculation of neutrino energy loss rates due to $^{24}$Mg in stellar matter. The rates are presented on a detailed density-temperature grid suitable for simulation purposes. The calculated neutrino energy loss rates are enhanced up to more than one order of magnitude compared to the shell model calculations and favor a lower entropy for the core of these massive stars.

  9. Decay studies of 59Cu* formed in the 35Cl + 24Mg reaction using the dynamical cluster-decay model

    Karthikraj, C.; Balasubramaniam, M.

    2013-02-01

    The reformulated dynamical cluster-decay model (DCM) is applied to study the decay of odd-A and non-α structured 59Cu* formed in the 35Cl+24Mg reaction at Elab=275 MeV. Here, the temperature (T)-dependent binding energies due to Krappe are used. The roles of Wigner and pairing energies in the fragmentation potential are explicitly shown in this work. For the temperature T=4.1898 MeV corresponding to Elab=275 MeV, the contribution of pairing vanishes and the resulting structure of the fragmentation potential due to Wigner term is shown. In addition to this, we have studied the role of factor α appearing in the inertia part of the equation of motion dictating the mass-transfer process. It is shown that this factor has significant effect in the structure of preformation probability values and hence in turn we see significant changes in the cross sections. We compare the cross sections of the measured charge distributions of the fission fragments for two limiting values of the parameter α with the experimental data. In order to fit the total cross-section values, a linear relation is obtained between the free parameter of the model ▵R and the factor α appearing in the hydrodynamical mass.

  10. Detailed microscopic calculation of stellar electron and positron capture rates on $^{24}$Mg for O+Ne+Mg core simulations

    Nabi, Jameel-Un

    2014-01-01

    Few white dwarfs, located in binary systems, may acquire sufficiently high mass accretion rates resulting in the burning of carbon and oxygen under nondegenerate conditions forming a O+Ne+Mg core. These O+Ne+Mg cores are gravitationally less bound than more massive progenitor stars and can release more energy due to the nuclear burning. They are also amongst the probable candidates for low entropy r-process sites. Recent observations of subluminous Type II-P supernovae (e.g., 2005cs, 2003gd, 1999br, 1997D) were able to rekindle the interest in 8 -- 10 M$_{\\odot}$ which develop O+Ne+Mg cores. Microscopic calculations of capture rates on $^{24}$Mg, which may contribute significantly to the collapse of O+Ne+Mg cores, using shell model and proton-neutron quasiparticle random phase approximation (pn-QRPA) theory, were performed earlier and comparisons made. Simulators, however, may require these capture rates on a fine scale. For the first time a detailed microscopic calculation of the electron and positron captur...

  11. Study of the angular correlations of light charged particles for the reaction 35CI (260 MeV) + 24Mg

    This work is focussed on the investigation of deformed nuclei. The asymmetric fusion-fission of light heavy-ions (A ≤60) with a high excitation energy (T ∼ 4 MeV) had lead to a large deformation of the compound nucleus at the scission point. The angular correlations between light particles (LP) and their emitting fragments has been used to probe the deformation of nucleus. Exclusive measurements were performed for the 35Cl (260 MeV) + 24Mg system leading to the 59Cu compound nucleus (CN). The comparison between the energy spectra of LP's and a statistical calculation carried out by a Monte-Carlo code CASCADE has suggested a deformation of 1.3 (for an oblate shape) of the CN within the frame work of fusion-evaporation process. The source velocity spectrum of α particles and angular correlations of LP's have showed that pre-scission and pre-equilibrium emissions are negligible in the present reaction. Finally the confrontation of the data with the statistical code GEMINI has pointed out the sequential emission character of the LP's from the fission fragments. (author)

  12. Analyses of electron and proton scattering to low excitation isoscalar states in 20Ne, 24Mg and 28Si

    Intermediate energy inelastic proton scattering differential cross section and polarization data from the 21+ states in 24Mg and 28Si and from the 41+ states in 28Si have been analysed using the Distorted Wave Approximation with large basis models of nuclear structure. These structure models were tested by use in analyses of the longitudinal form factors obtained from inelastic electron scattering, so that analyses of the intermediate energy (p,p') data from the same transitions are then sensitive tests of the two-nucleon t-matrix. Data from these and other 21+ transitions in 12C and 20Ne at 49 MeV (24 MeV in the case of 20Ne), were also analysed to compare models of t-matrices at lower energies. An ancilliary study of the momentum transfer dependence of effective charges has been made as both s-d shell and large basis structure models have been used to compare with form factor data up to momentum transfers of 2.5 fm-1. The deduced momentum dependence of the effective charges is significant

  13. Elastic and inelastic scattering of 400 MeV polarised deuterons on 12C, 24Mg, 40Ca nuclei

    This research thesis is based on an experiment of scattering of polarised 400 MeV deuterons on 12C, 24Mg, 40Ca nuclei, performed on the Saturne accelerator. The measured observables are the non-polarised cross section, and the powers of vector and tensor analysis. The author describes the experiment running and the installation, presents the various devices from source to detection and acquisition by the computer system. He reports the experiment compilation: reading of magnetic tapes, assessment and taking into account of the different experimental parameters. The calculation of scattering observables (cross section and powers of analysis) is performed by using experimental data. Spectra of these observables are represented for the different excited states of nuclei, after, should the occasion arise, Gaussian decomposition or background subtraction. The author reports the analysis of the obtained results. Results obtained for the three nuclei are compared between each other, and with scattering data for protons at similar energies which have already been measured. An analysis with a microscopic model is performed and the predictions of this model are compared with the obtained results

  14. Stellar neutrino energy loss rates due to 24Mg suitable for O+Ne+Mg core simulations

    Neutrino losses from proto-neutron stars play a pivotal role to decide if these stars would be crushed into black holes or explode as supernovae. Recent observations of subluminous Type II-P supernovae (e.g., 2005cs, 2003gd, 1999br, 1997D) were able to rejuvenate the interest in 8-10 M stars which develop O+Ne+Mg cores. Simulation results of O+Ne+Mg cores show varying results in converting the collapse into an explosion. The neutrino energy loss rates are important input parameters in core collapse simulations. Proton-neutron quasi-particle random phase approximation (pn-QRPA) theory has been used for calculation of neutrino energy loss rates due to 24Mg in stellar matter. The rates are presented on a detailed density-temperature grid suitable for simulation purposes. The calculated neutrino energy loss rates are enhanced up to more than one order of magnitude compared to the shell model calculations and favor a lower entropy for the core of these massive stars. (author)

  15. In-situ Electric Field-Induced Modulation of Photoluminescence in Pr-doped Ba0.85Ca0.15Ti0.90Zr0.10O3 Lead-Free Ceramics

    Sun, Hai Ling; Wu, Xiao; Chung, Tat Hang; Kwok, K. W.

    2016-06-01

    Luminescent materials with dynamic photoluminescence activity have aroused special interest because of their potential widespread applications. One proposed approach of directly and reversibly modulating the photoluminescence emissions is by means of introducing an external electric field in an in-situ and real-time way, which has only been focused on thin films. In this work, we demonstrate that real-time electric field-induced photoluminescence modulation can be realized in a bulk Ba0.85Ca0.15Ti0.90Zr0.10O3 ferroelectric ceramic doped with 0.2 mol% Pr3+, owing to its remarkable polarization reversal and phase evolution near the morphotropic phase boundary. Along with in-situ X-ray diffraction analysis, our results reveal that an applied electric field induces not only typical polarization switching and minor crystal deformation, but also tetragonal-to-rhombohedral phase transformation of the ceramic. The electric field-induced phase transformation is irreversible and engenders dominant effect on photoluminescence emissions as a result of an increase in structural symmetry. After it is completed in a few cycles of electric field, the photoluminescence emissions become governed mainly by the polarization switching, and thus vary reversibly with the modulating electric field. Our results open a promising avenue towards the realization of bulk ceramic-based tunable photoluminescence activity with high repeatability, flexible controllability, and environmental-friendly chemical process.

  16. Effect of oxidizing and reducing atmospheres on Ba(Ti0.90Zr0.10O3:2V ceramics as characterized by piezoresponse force microscopy

    Francisco Moura

    2011-09-01

    Full Text Available The effect of annealing atmospheres (At amb, N2 and O2 on the electrical properties of Ba(Ti0.90Zr0.10O3:2V (BZT10:2V ceramics obtained by the mixed oxide method was investigated. X-ray photoelectron spectroscopy (XPS analysis indicates that oxygen vacancies present near Zr and Ti ions reduce ferroelectric properties, especially in samples treated in an ambient atmosphere (At amb. BZT10:2V ceramics sintered in a nitrogen atmosphere showed better dielectric behaviour at room temperature with a dielectric permittivity measured at a frequency of 10 kHz equal to 16800 with dielectric loss of 0.023. Piezoelectric force microscopy (PFM images reveal improvement in the piezoelectric coefficient by sintering the sample under nitrogen atmosphere. Thus, BZT10:2V ceramics sintered under a nitrogen atmosphere can be useful for practical applications which include nonvolatile digital memories, spintronics and data-storage media.

  17. An attempt of application of short lived 44K activity induced in the 44Ca(n,p)44K reaction using 14 MeV neutrons for total body calcium assessment in human subject

    The status of in vivo neutron activation analysis techniques for the measurement of total body calcium in human subject is reviewed. Relevant data on the nuclear characteristics of calcium isotopes during interaction with neutrons ranging from slow up to 14 MeV neutrons are presented. Physical aspects of the measurement of in vivo total body calcium (TBCa) using 44K activity induced in the 44Ca(n,p)44K(T1/2=22.3 min) reaction by 14 MeV neutrons are discussed. The measurement of delayed γ-ray emitted during decay of activities induced in enriched 44Ca, natCa, phantom filled with water solution of natural calcium and skeletal arm are considered. Results of measurements on the phantom and skeletal arm indicate a possibility to measure the TBCa using the 44K activity. (author)

  18. Alpha-spectroscopic factors from (d,6Li) and (3He,7Be) reactions on 12C,24Mg,40Ca and 58Ni

    An attempt has been made to compare the alpha-spectroscopic factors (Ssub(α)) resulting from (d,6Li) and (3He,7Be) reactions on 12C,24Mg,40Ca and 58Ni employing potentials characterizing the same potential family for the deuteron and for the 3He-channels and another set of potentials characterizing a particular potential family for 6Li and 7Be-channels respectively. It is found that the extracted spectroscopic factors for 12C,24Mg and 40Ca agree well, while that for the target 58Ni differs by an order of magnitude from the other two reactions. A possible reason has been discussed. (author)

  19. Mass spectra and fusion cross sections for 20Ne + 24Mg interaction at 55 MeV and 85 MeV

    Inclusive γ-spectra from the 20Ne + 24Mg interaction have been measured using 55 and 85 MeV 20Ne beams accelerated at the CYCLONE cyclotron of Louvain-la-Neuve. The identification of γ lines allows the determination of mass spectra in the region 12<=A<=43. Experimental results are compared with statistical model calculations. The total reaction and fusion cross sections are extracted. Cross sections for inelastic scattering, few nucleon transfers and deep inelastic scattering are estimated. (author)

  20. The study of nuclear structure of 76-78Kr and 24Mg nuclei in the frame work of interacting boson model

    The results of this work show that the IBM-1 provides a good description of even-even 76-78Kr and 24Mg isotopes of the nuclei. The interacting boson model can reproduce a considerable quantity of experimental data and gives useful indications where data are lacking. One observe the transitions between three limit symmetries of the model, corresponding to different nuclear shapes

  1. Semi empirical formula for electronic stopping power determination of 24Mg, 27Al and 28Si ions crossing Formvar foil in the ion energy domain of LSS theory

    We have determined continuous stopping power of heavy ions in thin Formvar foil for 28Si, 27Al and 24Mg ions over an energy range of (0.1–0.5) MeV/nucleon. Heavy Ions Elastic Recoil Detection Analysis (HI-ERDA) technique coupled with time of flight (ToF) spectrometer has been used to measure energy loss of charged particles in this thin absorber. Lindhard, Scharff and Schiott (LSS) theory compared with the corresponding determined stopping values in Formvar, shows significantly large deviations. However, a novel semi empirical expression has been proposed here and tested for better stopping power calculations at low velocity in the ion energy domain of LSS theory for 28Si, 27Al and 24Mg ions crossing thin Formvar foil. The results were compared to the obtained experimental stopping power data, predictions of LSS theory and also to those generated by SRIM-2010 computer code. The obtained results exhibit good agreement with experimental data. - Highlights: • Experimental stopping data has been obtained by using Heavy Ions Elastic Recoil Detection Analysis technique with Time of Flight spectrometer. • A new semi-empirical stopping formula based on LSS theory has been proposed for 28Si, 27Al and 24 Mg ions in Formvar foil. • This expression well fit the experimental stopping data at low energy in LSS domain

  2. Study of the neutron decays of giant resonances excited by the inelastic scattering of {sup 36} Ar on {sup 90} Zr and {sup 94} Zr targets at 44 MeV/u: a signature of multiphonon states; Etude des decroissances par neutrons des resonances geantes excitees dans les reactions de diffusion inelastique d`{sup 36}Ar sur des cibles de {sup 90} Zr et {sup 94} Zr a 44MeV/u: une signature des etats multiphonons

    Pascalon-Rozier, V.

    1997-01-13

    In inelastic heavy ion scattering, to angles near to the grazing angle, giant resonances (GR) are excited with very large differential cross sections. It has been shown that multiphonon states, states built with several GR quanta, can also been excited. These states can be revealed through the measurement of their decay by light particle emission. In this thesis, we report on the study of inelastic scattering of {sup 36}Ar at 44 MeV/u on target of {sup 90}Zr and {sup 94}Zr, measured in coincidence with neutrons detected with the EDEN multidetector. The analysis of the inelastic spectra show evidence for a structure at high excitation energy, exhibiting characteristics compatible with a two-photon excitation. The construction of missing energy spectra allows us to the study of the GR and the high energy structure. In both nuclei, the GR presents a direct decay branch of 8%, which yields informations on the microscopic structure of the resonance. A two phonon state, interpreted as two weakly coupled GR`s, built on one top of the other, and each phonon is expected to exhibit the same direct decay pattern as the GR. Such a simple decay is observed in the data, proving that the structure observed is due to the excitation of the two phonon state in both nuclei studied. Finally, we present a theoretical development based on Random Phase Approximation calculation, predicting that the two phonon state should be very harmonic. This result is in agreement with experimental studies of double phonon states over a large range of nuclei (from A = 12 to 208) carried out with several different probes. (author). 70 refs.

  3. Activation cross section measurements near threshold for the 24Mg(n,p)24Na and 27Al(n,α)24Na reactions

    Differential cross sections have been measured for the 24Mg(n,p)24Na and 27Al(n,α)24Na reactions in the neutron energy range from near-threshold to approx. 10 MeV using 238U fast-neutron fission as a cross section standard. The present data generally support previous work, although the cross sections tend to be somewhat larger for 27Al(n,α)24Na, particularly in the 8-9 MeV range. These data contribute significantly to reducing the uncertainty in contemporary knowledge of the cross sections for these reactions in the threshold region. (author)

  4. 24Mg(α,γ)28Si reaction at alpha-particle energies from 3.2 to 6.2 MeV

    The 24Mg(α,γ)28Si reaction has been used to study excited states in 28Si. Targets of enriched 24Mg on a tantalum backing were bombarded by an α-particle beam from the CN Van de Graaff accelerator of The Pennsylvania State University. A large NaI(Tl) detector was placed immediately adjacent to the target in order to increase the probability of summing of the signals from different members of a cascade; windows were set for transitions to the ground state and the first few excited states. The energy of the α-particles was increased in steps of 2 to 5 keV from 3.2 to 6.2 MeV. Thirty-two resonances were located by sharp increases in the number of events recorded. At each resonance a spectrum was taken using a 55 cm3 Ge(Li) detector placed 5 cm from the target at an angle of 550 to the beam axis, the data being recorded on a PDP-15 on-line computer. The spectra were analyzed off-line using the program SAMPO of the Lawrence Berkeley Laboratory. (Diss. Abstr. Int., B)

  5. γ-ray production by proton and α-particle induced reactions on 12C, 16O, 24Mg, and Fe

    γ-ray production cross sections for proton and α-particle interactions with 12C, 16O, 24Mg, and Fe have been measured in the energy range 5-25 MeV with proton beams and 5-40 MeV with α-particle beams. Isotopically pure foils of 24Mg and foils of natural isotopical composition of C, MgO, and Fe have been used. γ-ray angular distributions were obtained with five high-purity Ge detectors with bismuth germanate Compton shields placed at angles of 45 deg. to 157.5 deg. Cross sections for more than 50 different γ-ray transitions were extracted, and for many of them no data have been published before. Comparison of present data with data available in the literature shows mostly good to excellent agreement. In addition to the production cross sections, high-statistics, low-background line shapes of the 4.438 MeV 12C γ ray from inelastic scattering off 12C and spallation of 16O were obtained. Comparison with nuclear reaction calculations shows that these data place interesting constraints on nuclear reaction models

  6. Dirac Coupled-channel Analyses of Polarized Proton Scatterings to the 2$^+$ Gamma Vibrational Band in $^{24}$Mg and $^{26}$Mg

    Shim, Sugie

    2016-01-01

    Dirac coupled channel calculations are performed phenomenologically for the high-lying excited states that belong to the 2$^+$ gamma vibrational band at the 800-MeV polarized proton inelastic scatterings from the s-d shell nuclei, $^{24}$Mg and $^{26}$Mg. Optical potential model is used and scalar and time-like vector potentials are considered as direct potentials. First-order vibrational collective models are used to obtain the transition optical potentials in order to accommodate the high-lying excited vibrational collective states. The complicated Dirac coupled channel equations are solved phenomenologically to reproduce the differential cross section and analyzing power data by varying the optical potential and deformation parameters. It is found that the relativistic Dirac coupled channel calculation could describe the high-lying excited states of the 2$^+$ gamma vibrational band at the 800-MeV polarized proton inelastic scatterings from s-d shell nuclei $^{24}$Mg and $^{26}$Mg reasonably well, showing b...

  7. $^{8}$Be, $^{12}$C, $^{16}$O, $^{20}$Ne, $^{24}$Mg, and $^{32}$S nuclei and alpha clustering within a generalized liquid drop model

    Royer, G; Eudes, P

    2015-01-01

    The potential energy governing the shape and the entrance and decay channels of the 12 C, 16 O, 20 Ne, 24 Mg, and 32 S 4n-nuclei has been determined within a generalized liquid drop model. Different three-dimensional and planar shapes have been investigated: linear chain, triangle, square, tetrahedron, pentagon, trigonal bipyramid, square pyramid, hexagon, octahedron, octogon and cube. The rms radii of the linear chains are higher than the experimental rms radii of the ground states. The binding energies of the planar shapes at the contact point are lower than the ones of the three-dimensional configurations. The a particle plus A-4 daughter configuration leads always to the lowest potential barrier relatively to the sphere configuration.

  8. Study of two- and multi-particle correlations in 12C+24Mg and 12C+208Pb reactions at E=35 AMeV

    Quattrocchi L.

    2016-01-01

    Full Text Available Two and multi particle correlations from the decay of sources produced in 12C+24Mg and 12C+208Pb collisions at E=35 AMeV have been studied by using the forward part (1° < θlab < 30° of the CHIMERA multi-detector. Correlations and invariant mass spectroscopy are used to explore simultaneous and sequential decays of resonances in light isotopes with Z∼3-6, produced in peripheral collisions via the break-up of excited quasi-projectiles. Among them we mention 5Li, 6Li, 6Be, 8Be and the astrophysically important state in 12C decaying into three alpha particles. Results and future perspectives at the INFN-LNS will be presented.

  9. Clustering effects in fusion evaporation reactions with light even-even N = Z nuclei. The {sup 24}Mg and {sup 28}Si cases

    Morelli, L., E-mail: luca.morelli@bo.infn.it; D’Agostino, M.; Bruno, M. [Dipartimento di Fisica e Astronomia dell’Università and INFN, Bologna (Italy); Baiocco, G. [Dipartimento di Fisica dell’Università and INFN, Pavia (Italy); Gulminelli, F. [CNRS, LPC, Caen, France and ENSICAEN, Caen (France); Cinausero, M.; Gramegna, F.; Marchi, T. [INFN, Laboratori Nazionali di Legnaro, Legnaro (Padova) (Italy); Degerlier, M. [University of Nevsehir, Physics Department, Nevsehir (Turkey); Fabris, D. [INFN, Sezione di Padova, Padova (Italy); Barlini, S.; Bini, M.; Casini, G.; Gelli, N.; Olmi, A.; Pasquali, G.; Piantelli, S. [Dipartimento di Fisica e Astronomia dell’Università and INFN, Firenze (Italy)

    2015-10-15

    In the recent years, cluster structures have been evidenced in many ground and excited states of light nuclei [1, 2]. Within the currently ongoing experimental campaign by the NUCL-EX collaboration we have measured the {sup 12}C+{sup 12}C and {sup 14}N+{sup 10}B reactions at 95 MeV and 80 MeV respectively, and compared experimental data corresponding to complete fusion of target and projectile into an excited {sup 24}Mg nucleus to the results of a pure statistical model[3, 4]. We found clear deviations from the statstical model in the decay pattern: emission channels involving multiple α particles are more probable than expected from a purely statistical behavior. To continue the investigation on light systems, we have recentely measured the {sup 16}O+{sup 12}C reaction at three different beam energies, namely E{sub beam} = 90, 110 and 130 MeV.

  10. Clustering effects in fusion evaporation reactions with light even-even N = Z nuclei. The 24Mg and 28Si cases

    In the recent years, cluster structures have been evidenced in many ground and excited states of light nuclei [1, 2]. Within the currently ongoing experimental campaign by the NUCL-EX collaboration we have measured the 12C+12C and 14N+10B reactions at 95 MeV and 80 MeV respectively, and compared experimental data corresponding to complete fusion of target and projectile into an excited 24Mg nucleus to the results of a pure statistical model[3, 4]. We found clear deviations from the statstical model in the decay pattern: emission channels involving multiple α particles are more probable than expected from a purely statistical behavior. To continue the investigation on light systems, we have recentely measured the 16O+12C reaction at three different beam energies, namely Ebeam = 90, 110 and 130 MeV

  11. Clustering effects in fusion evaporation reactions with light even-even N=Z nuclei. The 24Mg and 28Si cases

    Morelli, L.; Bruno, M.; D'Agostino, M.; Baiocco, G.; Gulminelli, F.; Cinausero, M.; Degerlier, M.; Fabris, D.; Gramegna, F.; Marchi, T.; Barlini, S.; Bini, M.; Casini, G.; Gelli, N.; Pasquali, G.; Piantelli, S.; Valdrè, S.

    2016-06-01

    In the recent years, cluster structures have been evidenced in many ground and excited states of light nuclei [1, 2]. The decay of highly excited states of 24Mg is studied in fusion evaporation events completely detected in charge in the reactions 12C+12C and 14N+10B at 95 and 80 MeV incident energy, respectively, and compared to the results of a pure statistical model [3, 4]. Inclusive variables are in general well reproduced by the model. We found clear deviations from the statistical model if we select emission channels involving multiple α particles which are more probable than expected from a purely statistical behavior. Data from 12C+12C reaction have been analyzed in order to study the decay of the Hoyle state of 12C* with two different selections: peripheral binary collisions and 6α decay channel in central events. To continue the investigation on light systems, we have recently measured the 16O+12C reaction at three different beam energies, namely Ebeam = 90, 110 and 130 MeV. Preliminary results are presented.

  12. Additional evidence for fusion-fission in 32S+24Mg reactions: Division of excitation energy and spin in the fission fragments

    We have measured γ rays in coincidence with 12C fragments from the fission of 56Ni produced with the 32S+24Mg reaction at Elab=140 MeV. These data provide insight into the fission process in this light system by giving information about the energy and spin sharing between the 12C and 44Ti fragments, and the spin alignment of the lighter, 12C fragment. The spin transfer and the nuclear ''temperature'' at scission deduced from this measurement can be related to the compound-nucleus spin and potential energy at scission. The results indicate a statistical decay process consistent with the predictions of the transition-state model employing newer estimates of the spin- and mass-asymmetry-dependent saddle-point energies and corresponding shapes. No evidence is found for the spin alignment of the 12C fragments, contrary to what might be expected for a deep-inelastic scattering origin of the fully energy damped yields

  13. (d, t) and (d, 3He) reactions on 12C, 16O, 24Mg, and 40Ca at 29 MeV

    The (d,t) and (d,3He) reactions on targets of 12C, 16O, 24Mg,and 40Ca leading to prominent low-lying analog states in the residual nuclei have been studies by measuring differential cross sections and vector analyzing powers. The cross section angular distributions at best exhibit only a weak sensitivity to the transferred angular momentum while the vector analyzing powers are strongly sensitive to the transferred angular momentum and provide a useful signature of the j transfer. Zero-range distorted-wave Born approximation predictions describe the sigma (theta) angular distributions quite well for the lighter targets while they only partially succeed in describing the A/sub y/(theta) for the lighter targets. An improved distorted-wave Born approximation description was obtained for the 40Ca target. Some sensitivity to the choice of optical parameters in the distorted-wave Born approximation analysis, particularly obvious in the A/sub y/(theta) predictions was seen. Values of extracted spectroscopic factors were generally consistent with those reported in other work

  14. Study of the angular correlations of light charged particles for the reaction {sup 35}CI (260 MeV) + {sup 24}Mg; Etude des correlations angulaires de particules legeres chargees dans la reaction {sup 35}CI (260 MeV) + {sup 24}Mg

    Mahboub, D.

    1996-10-30

    This work is focussed on the investigation of deformed nuclei. The asymmetric fusion-fission of light heavy-ions (A {<=}60) with a high excitation energy (T {approx} 4 MeV) had lead to a large deformation of the compound nucleus at the scission point. The angular correlations between light particles (LP) and their emitting fragments has been used to probe the deformation of nucleus. Exclusive measurements were performed for the {sup 35}Cl (260 MeV) + {sup 24}Mg system leading to the {sup 59}Cu compound nucleus (CN). The comparison between the energy spectra of LP`s and a statistical calculation carried out by a Monte-Carlo code CASCADE has suggested a deformation of 1.3 (for an oblate shape) of the CN within the frame work of fusion-evaporation process. The source velocity spectrum of {alpha} particles and angular correlations of LP`s have showed that pre-scission and pre-equilibrium emissions are negligible in the present reaction. Finally the confrontation of the data with the statistical code GEMINI has pointed out the sequential emission character of the LP`s from the fission fragments. (author). 175 refs.

  15. Piezoelectric properties of new ternary Bi1/2(Na, Li)1/2TiO3-(Bi1/2K1/2)TiO3-Ba0.85Ca0.15Ti0.90Zr0.10O3 ceramics

    0.852[Bi1/2(Na1-x Lix)1/2]TiO3-0.110(Bi1/2K1/2)TiO3-0.038Ba0.85Ca0.15Ti0.90Zr0.10O3 (BNLT-BKT-BCTZ-x) new ternary piezoelectric ceramics were fabricated by the conventional solid-state method, and their piezoelectric properties as a function of the Li content were mainly investigated. A stable solid solution with a single perovskite structure has been formed, and the depolarization temperature (Td) of these ceramics was identified by using the temperature dependence of the dielectric loss. The Td value of these ceramics gradually decreases, while the Tm value increases with increasing the Li content. The dielectric constant increases and the dielectric loss decreases with increasing the Li content, and an enhanced piezoelectric behavior of d33∝223 pC/N and kp∝35.2 % has been demonstrated in these ceramics with x=0.06. (orig.)

  16. /sup 12/C(/sup 16/O,. cap alpha. )/sup 24/Mg( reaction in the energy region E/sub c. m. / = 26. 6 to 42. 9 MeV

    Bechara, M.J.; Lazzarini, A.J.; Ledoux, R.J.; Cosman, A.E.R.

    1983-04-01

    The /sup 12/C+ /sup 16/O resonance structure in the /sup 28/Si nucleus is examined by means of the /sup 12/C(/sup 16/O,..cap alpha..)/sup 2r/Mg reaction excitation functions in the energy range E/sub c.m./ = 26.6 to 42.9 MeV in 430 keV steps at theta/sub lab/ = 7.5/sup 0/. We could identify 64 discrete states in /sup 24/Mg up to 31.7 MeV of excitation energy. The excitation functions show abundant structure over the entire energy range. The summed excitation functions, which tend to average out statistical fluctuations, show pronounced intermediate structure enhancement in the cross section at E/sub c.m./approx. =29.5, 32.2, and 35 MeV and indicate the presence of a smaller peak at 37.3 MeV. The widths of these structures are about 1 MeV, which is intermediate between the value expected from ion-ion potential resonances and statistical fluctuations. The nonstatistical character of these structures is reinforced by some statistical tests and by the correlations in energy and width found in several exit channels. Our data also suggest a possible structural relationship between the /sup 28/Si resonances and certain /sup 24/Mg final states.

  17. Investigation of exotic modes of spinning nuclei near 90Zr

    R Palit; S Saha

    2014-04-01

    Recently, a digital data acquisition system with 96 channels has been set up for the Indian National Gamma Array (INGA) consisting of 24 Compton-suppressed clover detectors. The digital system provides higher throughput, better energy resolution and better stability for the multidetector Compton-suppressed clover array compared to the previous conventional system with analog shaping. A number of nuclear spectroscopic experiments have been carried out using the array. Selected results from this array will be presented which highlight different excitations of nuclei near-shell gaps.

  18. Incomplete fusion and preequilibrium emission in the reactions 40Ar + 45Sc, 40Ar + 24Mg, 40Ar + 13C at 27.5 MeV by nucleon

    The evaporation residues were detected by means of a heavy ion time of flight system. As an attempt to examine in detail incomplete fusion for medium and light mass systems we have studied the reactions with experimental conditions allowing a complete separation and identification of the final products. We have analysed the velocity of the evaporation residues. The preequilibrium particles appear to be governed by two different regimes. The results show clearly that various compound nuclei are formed in the incomplete fusion process. The 40Ar + 13C reaction appears to be a special case. In the 40Ar+24Mg reaction, the study of preequilibrium particles in coincidence with evaporation residues confirms the results suggested for the heavy fragments

  19. Differential cross section measurements of 27Al(p,p/γ)27Al and 27Al(p,αγ)24Mg reactions in the energy range of 1.6-3.0 MeV

    Jokar, A.; Kakuee, O.; Lamehi-Rachti, M.; Sharifzadeh, N.; Fathollahi, V.

    2015-11-01

    In this work measurement of differential cross sections of 27Al(p,p/γ)27Al (Eγ = 844, 1014 keV) and 27Al(p,αγ)24Mg (Eγ = 1369 keV) nuclear reactions in the proton energy range of 1.6-3.0 MeV are described and the measured values are presented. Thin Al target was prepared by evaporating a 26 μg/cm2 Al onto a 129 μg/cm2 self-supporting Ag film. The gamma-rays and backscattered protons were detected simultaneously. The gamma-rays and protons were collected by an HPGe detector placed at an angle of 90° with respect to beam direction and an ion implanted Si detector placed at a scattering angle of 165°, respectively. In this experimental setup the great advantage is that differential cross sections could be independent on absolute values of the collected beam charge. The overall systematic uncertainty of cross sections was estimated to be ±9% while statistical errors were less than ±5%.

  20. Toward accurate thermochemistry of the {sup 24}MgH, {sup 25}MgH, and {sup 26}MgH molecules at elevated temperatures: Corrections due to unbound states

    Szidarovszky, Tamás [MTA-ELTE Research Group on Complex Chemical Systems, P.O. Box 32, H-1518 Budapest 112 (Hungary); Császár, Attila G., E-mail: csaszar@chem.elte.hu [MTA-ELTE Research Group on Complex Chemical Systems, P.O. Box 32, H-1518 Budapest 112 (Hungary); Laboratory on Molecular Structure and Dynamics, Institute of Chemistry, Eötvös University, Pázmány Péter sétány 1/A, H-1117 Budapest (Hungary)

    2015-01-07

    The total partition functions Q(T) and their first two moments Q{sup ′}(T) and Q{sup ″}(T), together with the isobaric heat capacities C{sub p}(T), are computed a priori for three major MgH isotopologues on the temperature range of T = 100–3000 K using the recent highly accurate potential energy curve, spin-rotation, and non-adiabatic correction functions of Henderson et al. [J. Phys. Chem. A 117, 13373 (2013)]. Nuclear motion computations are carried out on the ground electronic state to determine the (ro)vibrational energy levels and the scattering phase shifts. The effect of resonance states is found to be significant above about 1000 K and it increases with temperature. Even very short-lived states, due to their relatively large number, have significant contributions to Q(T) at elevated temperatures. The contribution of scattering states is around one fourth of that of resonance states but opposite in sign. Uncertainty estimates are given for the possible error sources, suggesting that all computed thermochemical properties have an accuracy better than 0.005% up to 1200 K. Between 1200 and 2500 K, the uncertainties can rise to around 0.1%, while between 2500 K and 3000 K, a further increase to 0.5% might be observed for Q{sup ″}(T) and C{sub p}(T), principally due to the neglect of excited electronic states. The accurate thermochemical data determined are presented in the supplementary material for the three isotopologues of {sup 24}MgH, {sup 25}MgH, and {sup 26}MgH at 1 K increments. These data, which differ significantly from older standard data, should prove useful for astronomical models incorporating thermodynamic properties of these species.

  1. Evaluation of cross-section data from threshold to 40-60 MeV for specific neutron reactions important for neutron dosimetry applications. Part 1: Evaluation of the excitation functions for the 27Al(n,α)24Na, 55Mn(n,2n)54Mn, 59Co(n,p)59Fe, 59Co(n,2n)58m+gCo and 90Zr(n,2n)89m+gZr reactions

    Evaluations of cross sections and their associated covariance matrices have been carried out for five dosimetry reactions: - excitation functions were re-evaluated for the 27Al(n,α)24Na, 55Mn(n,2n)54Mn and 90Zr(n,2n)89m+gZr reactions over the neutron energy range from threshold to 40 MeV; - excitation functions were re-evaluated for the 59Co(n,p)59Fe and 59Co(n,2n)58m+gCo reactions over the neutron energy range from threshold to 60 MeV. Uncertainties in the cross sections for all of those reactions were also derived in the form of relative covariance matrices. Benchmark calculations performed for 235U thermal fission and 252Cf spontaneous fission neutron spectra show that the integral cross sections calculated from the newly evaluated excitation functions exhibit improved agreement with related experimental data when compared with the equivalent data from the IRDF-2002 library. (author)

  2. Energy loss straggling data of 28Si, 27Al, 24Mg, 19F, 16O, and 12C heavy ions in thin polymeric Formvar foil over a range of energies 0.1–0.6 MeV/u by time-of-flight spectrometry

    The energy-loss straggling of 28Si, 27Al, 24Mg, 19F, 16O and 12C partially stripped heavy ions has been determined in Formvar polymeric thin foil over a continuous range of energies 0.1–0.6 MeV/u, by using a powerful method based on the combination of Heavy Ion-Elastic Recoil Detection Analysis (HI-ERDA) technique and Time of Flight (ToF) spectrometer. The obtained energy loss straggling values have been analyzed and compared with the corresponding computed values adopting some widely used energy loss straggling formulations such as, Bohr, Bethe–Livingston and Yang formulas. The aim of such a comparison is to check the reliability and accuracy of the existing energy loss straggling formulations. The experimental results of energy loss straggling of all ions are found to be significantly greater than those predicted by the theories. These differences can be attributed to the charge exchange straggling. This effect has to be taken into account in order to explain the obtained results. - Highlights: • Measurement of energy loss straggling data of 28Si, 27Al, 24Mg, 19F, 16O, and 12C heavy ions in thin polymeric Formvar foil. • The heavy ion elastic recoil detection analysis (HIERDA) technique coupled with time of flight (ToF) spectrometer was used. • The aim of such a study is to check the reliability and accuracy of the existing energy loss straggling formulations

  3. Gamow-Teller Resonance of 90Zr in a Relativistic Approach

    MAZhong-yu; CHENBao-qiu

    2003-01-01

    We establish the formalism of nuclear spin-isospin excitations, especially the Gamow-Teller (GT) resonance in a fully consistent relativistic random phase approximation. A relativistic form of the Landau-Migdal parameter g'=0.6 is adopted as a residual spin-isospin correlation force. In the non-relativistic limit it reproduces the excitation energy of the giant Gamow-Teller resonance state obtained in the non-relativistic model.

  4. Inelastic heavy ion scattering on 90Zr and 208Pb at intermediate energies

    Heavy ion inelastic scattering has been investigated using the SPEG spectrometer at GANIL. It is shown that the use of such a high resolution spectrometer allows a quantitative study of the giant resonances excited in heavy ion collisions. The contribution of the pick-up break-up mechanism to the high excitation energy region (E > 30 MeV) is then discussed. Recent results obtained with 40Ar beams at two different incident energies show that target excitations are also present in this energy region

  5. Measurements of the 24Mg(d,p0,1,2,3,4) and natMg(d,d0) reactions cross sections in the energy range of 1.2-2 MeV for NRA and EBS applications

    Rafi-kheiri, H.; Kakuee, O.; Lamehi-Rachti, M.

    2016-04-01

    Differential cross sections of the 24Mg(d,p0,1,2,3,4) reactions were obtained in the range Ed,lab = 1.2-2 MeV and at the scattering angles of 90°, 135°, 150° and 165° using a thin Mg target having thickness of 76.7 ± 3.1 μg/cm2. The cross section values were determined with an average energy step of ∼25 keV while the detailed measurements were carried out with an energy step of ∼5 keV around the resonance peaks. Elastic scattering data for three steep backward angles (135°, 150° and 165°) were also studied for the same incident deuteron energy range and steps. The results were compared with those of the previous studies. Moreover, the validity of the measured data has been benchmarked using a thick Mg target at two deuteron beam energies of 1.7 and 2 MeV.

  6. Seasonal Sr/Ca, and 44Ca/40Ca co-variation in Arctica islandica

    Full text: We have studied the Ca isotopic variations and Sr/Ca ratios within an A. islandica shell in relation to temperature fluctuations of the ambient seawater with sub-seasonal resolution. The long-lived bivalve A. islandica dwells at 10-200 m depth throughout much of the North Atlantic continental shelf. Its shells represent a promising SST archive for boreal marine settings. The A. islandica shell used for this study was collected at 60-m depth near the former position of the Nantucket Shoals Lightship. The years 1956-1958 were analyzed for both, Sr/Ca ratios and δ44/40Ca, with 1957 being the best resolved. The δ44/40Ca are highly correlated with Sr/Ca ratios (r= 0.92 for 1957). The positive correlation of Sr/Ca ratios and temperature in A. islandica is in accordance with published data on other bivalves, but contrary to thermodynamic expectations and e.g. coral data. The same inversion is found for Ca isotope fractionation: the δ44/40Ca correlation with temperature of A. islandica is negative, while all δ44/40Ca temperature gradients published so far (inorganic precipitates and foraminifera data) show varying degrees of positive correlation. Thus, as for Sr/Ca, the temperature correlation of δ44/40Ca in A. islandica is not under thermodynamic control. It appears inevitable to conclude that biological effects dominate both, Sr incorporation and Ca isotope fractionation in A. islandica. Growth rates and food supply are parameters that might relate Sr/Ca ratios as well as Ca isotopic compositions to vital activity and thus indirectly to temperature. In any case the high correlation of Sr/Ca ratios and Ca isotope fractionation indicates a common metabolic process for the observed variations. (author)

  7. Investigation of the reaction 90Zr(p,γ) with in-beam γ-ray spectroscopy

    Erbacher Philipp; Endres A.; Glorius J.; Netterdon L.; Sonnabend K.; Thomas B; Zilges A.

    2015-01-01

    The p nucleus 92Mo is believed to be mainly produced through photodisintegration reactions in type II supernovae. However, this production scenario cannot solely account for the observed solar relative isotopic abundance of 92Mo. Additional production scenarios have been suggested to explain this discrepancy. One of these scenarios could be the production of 92Mo in type Ia supernovae via a chain of proton-capture reactions. To verify this scenario, an accurate knowledge of the involved react...

  8. Experimental investigation shell model excitations of 89Zr up to high spin and its comparison with 88,90Zr

    The excited states of nuclei near N=50 closed shell provide suitable laboratory for testing the interactions of shell model states, possible presence of high spin isomers and help in understanding the shape transition as the higher orbitals are occupied. In particular, the structure of N = 49 isotones (and Z =32 to 46) with one hole in N=50 shell gap have been investigated using different reactions. Interestingly, the high spin states in these isotones have contribution from particle excitations across the respective proton and neutron shell gaps and provide suitable testing ground for the prediction of shell model interactions describing theses excitations across the shell gap. In the literature, extensive study of the high spin states of heavier N = 49 isotones starting with 91Mo up to 95Pd are available. Limited information existed on the high spin states of lighter isotones. Therefore, the motivation of the present work is to extend the high spin structure of 89Zr and to characterize the structure of these levels through comparison with the large scale shell model calculations based on two new residual interactions in f5/2pg9/2 model space

  9. Re-evaluation of microscopic and integral cross-section data for important dosimetry reactions. Re-evaluation of the excitation functions for the 24Mg(n,p)24Na, 32S(n,p)32P, 60Ni(n,p)60m+gCo, 63Cu(n,2n)62Cu, 65Cu(n,2n)64Cu, 64Zn(n,p)64Cu, 115In(n,2n)114mIn, 127I(n,2n)126I, 197Au(n,2n)196Au and 199Hg(n,n')199mHg reactions

    Re-evaluations of cross sections and their associated covariance matrices have been carried out for ten dosimetry reactions: - excitation functions for the 63Cu(n,2n)62Cu, 65Cu(n,2n)64Cu, 64Zn(n,p)64Cu, 115In(n,2n)114mIn and 199Hg(n,n')199mHg reactions were re-evaluated over the neutron energy range from threshold to 20 MeV; - excitation functions for the 24Mg(n,p)24Na, 32S(n,p)32P and 60Ni(n,p)60m+gCo were reevaluated in the energy range from threshold to 21 MeV; - excitation functions for the 127I(n,2n)126I and 197Au(n,2n)196Au reactions were reevaluated in the energy range from threshold to 32 and 40 MeV, respectively. Benchmark calculations performed for 235U thermal fission and 252Cf spontaneous fission neutron spectra show that the integral cross sections derived from the newly evaluated excitation functions exhibit improved agreement with related experimental data when compared with the equivalent data from the IRDF-2002 library. (author)

  10. Cobalt silicide formation on a Si(1 0 0) substrate in the presence of an interfacial (Fe{sub 90}Zr{sub 10}) interlayer

    Abrass, Hameda A. [Department of Physics, University of Pretoria, Pretoria 0002 (South Africa); Theron, C.C., E-mail: Chris.Theron@up.ac.za [Department of Physics, University of Pretoria, Pretoria 0002 (South Africa); Njoroge, E.G.; Berg, N.G. van der; Botha, A.J. [Department of Physics, University of Pretoria, Pretoria 0002 (South Africa); Yan, X.-L.; Terblans, J.J. [Department of Physics, University of the Free State, Bloemfontein 9300 (South Africa)

    2015-09-15

    The reaction between a thin film (126 nm) of Co and Si has been studied at 450 °C for 24 h under high vacuum conditions, in the presence of a FeZr barrier layer. Without a diffusion barrier layer between Co and Si, Co{sub 2}Si forms at 350 °C as the initial phase while CoSi{sub 2} forms at 550 °C. The FeZr barrier layer changed the flux of atoms arriving at the reaction interface. Co reacted with the Si from the substrate and formed a mixed layer of CoSi and CoSi{sub 2} in the interlayer region. The use of the FeZr diffusion barrier has been demonstrated to lower the temperature formation of CoSi{sub 2} to 450 °C. The reactions were characterised by Rutherford backscattering spectrometry, Auger electron spectroscopy depth profiling, X-ray diffraction using CoK{sub α} radiation and scanning electron microscopy.

  11. Electromagnetic properties of the 01+, 21+, 41+, states in 20Ne, 24Mg, 28Si, 32S

    The 0+, 2+, 4+ sequence in the 4N nuclei in the 1s-0d shell has been examined by comparing the results of a large-basis shell-model calculation with electron scattering data. While the ground state is well described by the shell-model wave function there is evidence that extra s-d space configurations play an important role in defining the radial shapes of inelastic transition densities. For 0+ → 4+ transitions, mixing of the 0g shell is important. The Chung-Wildenthal interaction shows erroneous behaviour in the description of some of the electromagnetic properties of these states. (Auth.)

  12. Study of particle unbound states in 25Mg and 25Al nuclei by the reaction 24Mg(d,pn)

    Stripping reactions to unbound states in 25Mg and 25Al nuclei were investigated by measuring proton-neutron angular correlation. An analysis of triple differential cross sections has been given. New high excited unbound states in the energy range from 8.1 to 11.6 MeV for 25Mg and from 4.6 to 8.3 MeV for 25Al nuclei were observed. Angular distributions of double differential cross sections were found for most of the levels. (author)

  13. Remote frequency measurement of the 1S0-3P1 transition in laser cooled 24Mg

    Friebe, J; Wübbena, T; Pape, A; Kelkar, H; Ertmer, W; Terra, O; Sterr, U; Weyers, S; Grosche, G; Schnatz, H; Rasel, E M

    2011-01-01

    We perform Ramsey-Borde spectroscopy on laser cooled magnesium atoms in free fall to measure the 1S0-3P1 intercombination transition frequency. The measured value of 655 659 923 839 730 (48) Hz is consistent with our former atomic beam measurement. We improve upon the fractional accuracy of the previous measurement by more than an order of magnitude to 7 x 10^-14. The magnesium frequency standard was referenced to a fountain clock of the Physikalisch Technische Bundesanstalt (PTB) via a phase-stabilized telecom fiber link and its stability characterized for interrogation times up to 8000 s. Our measurement revealed a new systematic effect due to the movement of atoms across the spectroscopy beams. A remarkable property of this effect is the counterintuitive reduction of residual Doppler shift with increasing resolution. Our theoretical model of the atom-light interaction is in agreement with the observed effect and allows us to quantify its contribution in the uncertainty budget.

  14. Nuclear temperature anomaly in 35Cl+24Mg reaction at Ec.m.=105 MeV

    It was found earlier from studies on A∼100 mass region at (4-8) MeV/A bombarding energy that the temperatures obtained from the slopes of the spectra of the heavier evaporation fragments (such as α, Li, B, C etc.) were significantly higher than the expectations from statistical model calculations. We have now extended this investigation to lower mass region (A ∼60)

  15. Comparison between cross sections, saddle point and scission point barriers for the 32S+24Mg reaction

    One of the principal characteristics of nuclear multifragmentation is the emission of complex fragments of intermediate mass. The statistical multifragmentation model has been used for many years to describe the distribution of these fragments. An extension of the statistical multifragmentation model to include partial widths and lifetimes for emission, interprets the fragmentation process as the near simultaneous limit of a series of sequential binary decays. In this extension, the expression describing intermediate mass fragment emission is almost identical to that of light particle emission. At lower temperatures, similar expressions have been shown to furnish a good description of very light intermediate mass fragment emission. However, this is usually not considered a good approximation to the emission of heavier fragments. These emissions seem to be determined by the characteristics of the system at the saddle-point and its subsequent dynamical evolution rather than by the scission point. Here, we compare the barriers and decay widths of these different formulations of intermediate fragment emission and analyze the extent to which they remain distinguishable at high excitation energy. (author)

  16. Evaluation of clinical safety and anthelmintic efficacy of aurixazole administed orally at 24 mg/kg in cattle.

    Sakamoto, Claudio Alessandro M; Lopes, Welber Daniel Zanetti; Buzzulini, Carolina; Cruz, Breno Cayeiro; Felippelli, Gustavo; Teixeira, Weslen F; Silva, Helenara Machado; Santana, Luis Fernando; Soares, Vando Edésio; Henrique, Carlos Henrique; de Oliveira, Gilson Pereira; da Costa, Alvimar José

    2014-06-01

    The current study evaluated, in vivo, the clinical safety and the anthelmintic efficacy of 24% aurixazole (24 mg/kg), administered orally, in bovines. Two experiments were conducted: the first one evaluating the clinical safety of 24% aurixazole (24 mg/kg) in cattle, and a second one evaluating the anthelmintic efficacy of aurixazole (24 mg/kg) against gastrointestinal nematodes on naturally infected cattle. Based on the results of clinical safety, no alterations on clinical and haematological signs and on the biochemical values obtained in animals treated orally with aurixazole 24 mg/kg were observed. Regarding the results of reduction or efficacy, obtained by eggs per gram of faeces (EPG) counts, the formulation of aurixazole reached values superior to 99% (arithmetic means) in all post-treatment dates. In two occasions, this formulation reached maximum efficacy (100%). Comparing these results with the reduction percentages obtained by EPG counts, it is possible to verify that the values obtained by all three formulations were compatible with the efficacy results. Aurixazole reached maximum efficacy (100%) against Haemonchus placei, Cooperia spatulata and Oesophagostomum radiatum. Against Cooperia punctata, this formulation reached an efficacy index of 99.99%. Regarding aurixazole, no specific trials were conducted on the field in order to evaluate the behaviour of this molecule against helminths that are resistant to other molecules, specially isolated levamisole and disophenolat. Due to this fact, future studies will be necessary to assess the effectiveness of aurixazole against strains of nematodes that are resistant to levamisole and disophenolat, but the results of clinical safety and efficacy described in this study allow us to conclude that the aurixazole molecule, concomitantly with other measures and orally administered formulations, can be another important tool in the control of nematodes parasitizing bovines. PMID:24656344

  17. Analysis of 6Li Scattering at 240 MeV Using Different Nuclear Potentials

    Al-Ghamdi, A. H.; Ibraheem, Awad A.

    2016-06-01

    Angular distributions of the elastic and inelastic scattering cross sections of 6Li projectile on different heavy ion target nuclei including the 24Mg, 28Si, 48Ca, 58Ni, 90Zr, and 116Sn at energy of 240 MeV have been analyzed by using two different folded potentials based on the CDM3Y6 and São Paulo potentials for the real part of the optical potential, while the imaginary parts have a phenomenological Woods-Saxon shape. Coupled channel calculations for the low-lying 2+ state at 1.369, 1.779, 3.832, 1.454, 2.186, and 1.29 MeV for 24Mg, 28Si, 48Ca, 58Ni, 90Zr, and 116Sn, respectively, have been carried out, and the best fit values for B(EL) with the above models have been extracted by fitting the inelastic scattering cross section and compared with the values of previous works. The total reaction cross section and real and imaginary volume integrals have also been investigated.

  18. Stellar 30-keV neutron capture in 94,96Zr and the 90Zr(gamma,n)89Zr photonuclear reaction with a high-power liquid-lithium target

    Tessler, M; Arenshtam, A; Feinberg, G; Friedman, M; Halfon, S; Kijel, D; Weissman, L; Aviv, O; Berkovits, D; Eisen, Y; Eliyahu, I; Haquin, G; Kreisel, A; Mardor, I; Shimel, G; Shor, A; Silverman, I; Yungrais, Z

    2015-01-01

    A high-power Liquid-Lithium Target (LiLiT) was used for the first time for neutron production via the thick-target 7Li(p,n)7Be reaction and quantitative determination of neutron capture cross sections. Bombarded with a 1-2 mA proton beam at 1.92 MeV from the Soreq Applied Research Accelerator Facility (SARAF), the setup yields a 30-keV quasi-Maxwellian neutron spectrum with an intensity of 3-5e10 n/s, more than one order of magnitude larger than present near-threshold 7Li(p,n) neutron sources. The setup was used here to determine the 30-keV Maxwellian averaged cross section (MACS) of 94Zr and 96Zr as 28.0+-0.6 mb and 12.4+-0.5 mb respectively, based on activation measurements. The precision of the cross section determinations results both from the high neutron yield and from detailed simulations of the entire experimental setup. We plan to extend our experimental studies to low-abundance and radioactive targets. In addition, we show here that the setup yields intense high-energy (17.6 and 14.6 MeV) prompt cap...

  19. ZZ KAFAX-F31, 150 and 12 Groups Cross Section Library in MATXS Format based on JEFF-3.1 for Fast Reactors

    1 - Description: Format: MATXS, 142 nuclides processed with NJOY99.245. Number of groups: 150 neutron-, 12 photon-groups. 142 nuclides: H-1, H-2, He-3, He-4, Li-6, Li-7, Be-9, B-10, B-11, C-nat, N-14, N-15, O-16, F-19, Na-23, Mg-24, Mg-25, Mg-26, Al-27, Si-28, Si-29, Si-30, P-31, Cl-35, Cl-37, Ar-40, K-39, K-40, K-41, Ca-40, Ca-42, Ca-43, Ca-44, Ca-46, Ca-48, Ti-46, Ti-47, Ti-48, Ti-49, Ti-50, V-nat, Cr-50, Cr-52, Cr-53, Cr-54, Mn-55, Fe-54, Fe-56, Fe-57, Fe-58, Co-59, Ni-58, Ni-60, Ni-61, Ni-62, Ni-64, Cu-63, Cu-65, Ga-nat, Y-89, Zr-90, Zr-91, Zr-92, Zr-93, Zr-94, Zr-95, Zr-96, Nb-93, Mo-92, Mo-94, Mo-95, Mo-96, Mo-97, Mo-98, Mo-99, Mo-100, Ag-107, Ag-109, Cd-106, Cd-108, Cd-110, Cd-111, Cd-112, Cd-113, Cd-114, Cd-115m, Cd-116, Sn-112, Sn-114, Sn-115, Sn-116, Sn-117, Sn-118, Sn-119, Sn-120, Sn-122, Sn-123, Sn-124, Sn-125, Sn-126, Eu-151, Eu-153, Gd-152, Gd-154, Gd-155, Gd-156, Gd-157, Gd-158, Gd-160, W-182, W-183, W-184, W-186, Re-185, Re-187, Au-197, Pb-206, Pb-207, Pb-208, Bi-209, Th-232, Pa-233, U-233, U-234, U-235, U-236, U-238, Np-237, Pu-238, Pu-239, Pu-240, Pu-241, Pu-242, Am-241, Am-242, Am-242m, Am-243, Cm-242, Cm-243, Cm-244, Cm-245, Cm-246. Origin: JEFF-3.1. Weighting spectrum: 300, 600, 900, 1200 K. The KAFAX-F31 is a MATXS-format, 150-group neutron and 12-group photon cross section library for fast reactors based on JEFF-3.1. This library was originally generated for the KALIMER (Korea Advanced LIquid Metal Reactor) core analyses. It includes 142 nuclide data (Table 1) processed by the NJOY99.245 code patched with NEA020. The library can be utilized to generate the problem-dependent group constants for neutron and/or photon transport calculations through the DANTSYS, DOORS, or PARTISN code systems. 2 - Methods: The KAFAX-F31 was generated at 300, 600, 900, and 1200 K. It contains the self-shielded cross sections for 5 to 10 background cross sections depending on the nuclides. The neutron group structure consists of one-eighth lethargy widths in almost

  20. ZZ KAFAX-E70, 150 and 12 Groups Cross Section Library in MATXS Format based on ENDF/B-VII.0 for Fast Reactors

    1 - Description: Format: MATXS, 144 nuclides processed with NJOY99.245. Number of groups: 150 neutron-, 12 photon-groups. 144 nuclides: H-1, H-2, He-3, He-4, Li-6, Li-7, Be-9, B-10, B-11, C-nat, N-14, N-15, O-16, F-19, Na-23, Mg-24, Mg-25, Mg-26, Al-27, Si-28, Si-29, Si-30, P-31, Cl-35, Cl-37, Ar-40, K-39, K-40, K-41, Ca-40, Ca-42, Ca-43, Ca-44, Ca-46, Ca-48, Ti-46, Ti-47, Ti-48, Ti-49, Ti-50, V-nat, Cr-50, Cr-52, Cr-53, Cr-54, Mn-55, Fe-54, Fe-56, Fe-57, Fe-58, Co-59, Ni-58, Ni-60, Ni-61, Ni-62, Ni-64, Cu-63, Cu-65, Ga-69, Ga-71, Y-89, Zr-90, Zr-91, Zr-92, Zr-93, Zr-94, Zr-95, Zr-96, Nb-93, Mo-92, Mo-94, Mo-95, Mo-96, Mo-97, Mo-98, Mo-99, Mo-100, Ag-107, Ag-109, Cd-106, Cd-108, Cd-110, Cd-111, Cd-112, Cd-113, Cd-114, Cd-115m, Cd-116, Sn-112, Sn-113, Sn-114, Sn-115, Sn-116, Sn-117, Sn-118, Sn-119, Sn-120, Sn-122, Sn-123, Sn-124, Sn-125, Sn-126, Eu-151, Eu-153, Gd-152, Gd-154, Gd-155, Gd-156, Gd-157, Gd-158, Gd-160, W-182, W-183, W-184, W-186, Re-185, Re-187, Au-197, Pb-206, Pb-207, Pb-208, Bi-209, Th-232, Pa-233, U-233, U-234, U-235, U-236, U-238, Np-237, Pu-238, Pu-239, Pu-240, Pu-241, Pu-242, Am-241, Am-242, Am-242m, Am-243, Cm-242, Cm-243, Cm-244, Cm-245, Cm-246. Origin: ENDF/B-VII.0. Weighting spectrum: 300, 600, 900, 1200 k. The ZZ-KAFAX-E70 is a MATXS-format, 150-group neutron and 12-group photon cross section library for fast reactors based on ENDF/B-VII.0. This library was originally generated for the KALIMER (Korea Advanced Liquid Metal Reactor) core analyses. It includes 144 nuclide data processed with the NJOY99.245 code patched with NEA020. The library can be used to generate the problem-dependent group constants for neutron and/or photon transport calculations through the DANTSYS, DOORS, or PARTISN code systems. 2 - Methods: The KAFAX-E70 was generated at 300, 600, 900, and 1200 K. It contains the self-shielded cross sections for 5 to 10 background cross sections depending on the nuclides. The neutron group structure consists of one-eighth lethargy

  1. ZZ KAFAX-J33, 150 and 12 Groups Cross Section Library in MATXS Format based on JENDL-3.3 for Fast Reactors

    1 - Description: Format: MATXS, 136 nuclides processed with NJOY99.245. Number of groups: 150 neutron-, 12 photon-groups. 136 Nuclides: H-1, H-2, He-3, He-4, Li-6, Li-7, Be-9, B-10, B-11, C-nat, N-14, N-15, O-16, F-19, Na-23, Mg-24, Mg-25, Mg-26, Al-27, Si-28, Si-29, Si-30, P-31, Cl-35, Cl-37, Ar-40, K-39, K-40, K-41, Ca-40, Ca-42, Ca-43, Ca-44, Ca-46, Ca-48, Ti-46, Ti-47, Ti-48, Ti-49, Ti-50, V-nat, Cr-50, Cr-52, Cr-53, Cr-54, Mn-55, Fe-54, Fe-56, Fe-57, Fe-58, Co-59, Ni-58, Ni-60, Ni-61, Ni-62, Ni-64, Cu-63, Cu-65, Ga-69, Ga-71, Y-89, Zr-90, Zr-91, Zr-92, Zr-93, Zr-94, Zr-95, Zr-96, Mo-92, Mo-94, Mo-95, Mo-96, Mo-97, Mo-98, Mo-99, Mo-100, Ag-107, Ag-109, Cd-106, Cd-108, Cd-110, Cd-111, Cd-112, Cd-113, Cd-114, Cd-116, Sn-112, Sn-114, Sn-115, Sn-116, Sn-117, Sn-118, Sn-119, Sn-120, Sn-122, Sn-123, Sn-124, Sn-126, Eu-151, Eu-153, Gd-152, Gd-154, Gd-155, Gd-156, Gd-157, Gd-158, Gd-160, W-182, W-183, W-184, W-186, Pb-206, Pb-208, Bi-209, Th-232, Pa-233, U-233, U-234, U-235, U-236, U-238, Np-237, Pu-238, Pu-239, Pu-240, Pu-241, Pu-242, Am-241, Am-242, Am-242m, Am-243, Cm-242, Cm-243, Cm-244, Cm-245, Cm-246. Origin: JENDL-3.3. Weighting spectrum: 300, 600, 900, 1200 K. The KAFAX-J33 is a MATXS-format, 150-group neutron and 12-group photon cross section library for fast reactors based on JENDL-3.3. This library was originally generated for the KALIMER (Korea Advanced LIquid Metal Reactor) core analyses. It includes 136 nuclide data processed by the NJOY99.245 code patched with NEA020. The library can be utilized to generate the problem-dependent group constants for neutron and/or photon transport calculations through the DANTSYS, DOORS, or PARTISN code systems. 2 - Methods: The KAFAX-J33 was generated at 300, 600, 900, and 1200 K. It contains the self-shielded cross sections for 5 to 10 background cross sections depending on the nuclides. The neutron group structure consists of one-eighth lethargy widths in almost all the energy ranges, except between 1 and 10 keV in

  2. Clustering effects in fusion evaporation reactions with light even-even N=Z nuclei. The 24Mg and 28Si cases

    Morelli L.

    2016-01-01

    Inclusive variables are in general well reproduced by the model. We found clear deviations from the statistical model if we select emission channels involving multiple α particles which are more probable than expected from a purely statistical behavior. Data from 12C+12C reaction have been analyzed in order to study the decay of the Hoyle state of 12C* with two different selections: peripheral binary collisions and 6α decay channel in central events. To continue the investigation on light systems, we have recently measured the 16O+12C reaction at three different beam energies, namely Ebeam = 90, 110 and 130 MeV. Preliminary results are presented.

  3. Generation of high power cw laser light at 257 nm for laser cooling of intense 24Mg+ beams at the ESR

    We report on the generation of 750 mW cw laser radiation at a wavelength of 257 nm obtained by frequency doubling the green Ar+ line in a Brewster-cut BBO crystal placed in the spherical focus of an external ring resonator. The system is optimized for laser cooling studies of intense 83.7 MeV 21Mg+ ion beams at the ESR dedicated to the investigation of space charge-dominated beams

  4. The Role of Friction Stir Welding on the Microstructure and Mechanical Properties of AZ31B-H24 Mg alloy

    In this study, an attempt was made to join AZ31B magnesium alloy by friction stir welding (FSW) process. A single tool with cylindrical screw threaded pin was used to investigate the effect of welding parameters on microstructure and mechanical properties of stir zone (SZ). Several welds were made at different rotational (ω) and traverse (υ) speeds, while the ω/υ ratios were kept constant. The optical and scanning electron microscopy were used to study the variation of microstructure across the welds. Moreover, micro-hardness and tensile tests were carried out to evaluate the mechanical properties of joints. It was found that ω plays more significant role on the resulted grain structure than υ, and at a constant ω/υ ratio, decreasing rotational speed decreased the size of grains, and hence, improved the hardness value and the tensile strength of the SZ.

  5. ZZ MATXSLIBJ33, JENDL-3.3 based, 175 N-42 photon groups (VITAMIN-J) MATXS library for discrete ordinates multi-group

    1 - Description of program or function: JENDL-3.3 based, 175 neutron-42 photon groups (VITAMIN-J) MATXS library for discrete ordinates multi-group transport codes. Format: MATXS. Number of groups: 175 neutron, 42 gamma-ray. Nuclides: 337 nuclides contained in JENDL-3.3: H-1, H-2, He-3, He-4, Li-6, Li-7, Be-9, B-10, B-11, C-Nat, N-14, N-15, O-16, F-19, Na-23, Mg-24, Mg-25, Mg-26, Al-27, Si-28, Si-29, Si-30, P-31, S-32, S-33, S-34, S-36, Cl-35, Cl-37, Ar-40, K-39, K-40, K-41, Ca-40, Ca-42, Ca-43, Ca-44, Ca-46, Ca-48, Sc-45, Ti-46, Ti-47, Ti-48, Ti-49, Ti-50, V-Nat, Cr-50, Cr-52, Cr-53, Cr-54, Mn-55, Fe-54, Fe-56, Fe-57, Fe-58, Co-59, Ni-58, Ni-60, Ni-61, Ni-62, Ni-64, Cu-63, Cu-65, Ga-69, Ga-71, Ge-70, Ge-72, Ge-73, Ge-74, Ge-76, As-75, Se-74, Se-76, Se-77, Se-78, Se-79, Se-80, Se-82, Br-79, Br-81, Kr-78, Kr-80, Kr-82, Kr-83, Kr-84, Kr-85, Kr-86, Rb-85, Rb-87, Sr-86, Sr-87, Sr-88, Sr-89, Sr-90, Y-89, Y-91, Zr-90, Zr-91, Zr-92, Zr-93, Zr-94, Zr-95, Zr-96, Nb-93, Nb-94, Nb-95, Mo-92, Mo-94, Mo-95, Mo-96, Mo-97, Mo-98, Mo-99, Mo-100, Tc-99, Ru-96, Ru-98, Ru-99, Ru-100, Ru-101, Ru-102, Ru-103, Ru-104, Ru-106, Rh-103, Rh-105, Pd-102, Pd-104, Pd-105, Pd-106, Pd-107, Pd-108, Pd-110, Ag-107, Ag-109, Ag-110m, Cd-106, Cd-108, Cd-110, Cd-111, Cd-112, Cd-113, Cd-114, Cd-116, In-113, In-115, Sn-112, Sn-114, Sn-115, Sn-116, Sn-117, Sn-118, Sn-119, Sn-120, Sn-122, Sn-123, Sn-124, Sn-126, Sb-121, Sb-123, Sb-124, Sb-125, Te-120, Te-122, Te-123, Te-124, Te-125, Te-126, Te-127m, Te-128, Te-129m, Te-130, I-127, I-129, I-131, Xe-124, Xe-126, Xe-128, Xe-129, Xe-130, Xe-131, Xe-132, Xe-133, Xe-134, Xe-135, Xe-136, Cs-133, Cs-134, Cs-135, Cs-136, Cs-137, Ba-130, Ba-132, Ba-134, Ba-135, Ba-136, Ba-137, Ba-138, Ba-140, La-138, La-139, Ce-140, Ce-141, Ce-142, Ce-144, Pr-141, Pr-143, Nd-142, Nd-143, Nd-144, Nd-145, Nd-146, Nd-147, Nd-148, Nd-150, Pm-147, Pm-148, Pm-148m, Pm-149, Sm-144, Sm-147, Sm-148, Sm-149, Sm-150, Sm-151, Sm-152, Sm-153, Sm-154, Eu-151, Eu-152, Eu-153, Eu-154, Eu-155, Eu

  6. ZZ KASHIL-E70, 199 N, 42 Photon Groups Cross Sections in MATXS Format Based on ENDF/B-VII.0 for Shielding Applications

    1 - Description: Format: MATXS, 204 nuclides processed with NJOY99.245. Number of groups: 199 neutron-, 42 photon-groups. 204 Nuclides including 8 thermal scattering law data: H-1, H-2, H-3, He-3, He-4, Li-6, Li-7, Be-9, Be-9, Be-9, B-10, B-11, C-nat, C-nat, N-14, N-15, O-16, O-17, F-19, Na-23, Mg-24, Mg-25, Mg-26, Al-27, Si-28, Si-29, Si-30, P-31, S-32, S-33, S-34, S-36, Cl-35, Cl-37, K-39, K-40, K-41, Ca-40, Ca-42, Ca-43, Ca-44, Ca-46, Ca-48, Sc-45, Ti-46, Ti-47, Ti-48, Ti-49, Ti-50, V-nat, Cr-50, Cr-52, Cr-53, Cr-54, Mn-55, Fe-54, Fe-56, Fe-57, Fe-58, Co-59, Ni-58, Ni-60, Ni-61, Ni-62, Ni-64, Cu-63, Cu-65, Ga-69, Ga-71, Y-89, Zr-90, Zr-91, Zr-92, Zr-94, Zr-96, Nb-93, Mo-92, Mo-94, Mo-95, Mo-96, Mo-97, Mo-98, Mo-100, Pd-102, Pd-104, Pd-105, Pd-106, Pd-108, Pd-110, Ag-107, Ag-109, Cd-106, Cd-108, Cd-110, Cd-112, Cd-113, Cd-114, Cd-116, In-113, In-115, I-127, Xe-124, Xe-126, Xe-128, Xe-129, Xe-130, Xe-131, Xe-132, Xe-134, Xe-136, Cs-133, Ba-138, Pr-141, Nd-143, Nd-145, Nd-146, Nd-148, Nd-150, Pm-147, Sm-147, Sm-151, Sm-152, Eu-151, Eu-152, Eu-153, Eu-154, Eu-155, Gd-152, Gd-154, Gd-155, Gd-156, Gd-157, Gd-158, Gd-160, Dy-164, Ho-165, Lu-175, Lu-176, Hf-174, Hf-176, Hf-177, Hf-178, Hf-179, Hf-180, Ta-181, Ta-182, W-182, W-183, W-184, W-186, Re-185, Re-187, Ir-191, Ir-193, Au-197, Pb-206, Pb-207, Pb-208, Bi-209, Th-230, Th-232, Pa-231, Pa-233, U-232, U-233, U-234, U-235, U-236, U-237, U-238, Np-237, Np-238, Np-239, Pu-236, Pu-237, Pu-238, Pu-239, Pu-240, Pu-241, Pu-242, Pu-243, Pu-244, Am-241, Am-242, Am-242m, Am-243, Cm-241, Cm-242, Cm-243, Cm-244, Cm-245, Cm-246, Cm-247, Cm-248, Bk-249, Cf-249, Cf-250, Cf-251, Cf-252, Cf-253, Es-253. Origin: ENDF/B-VII.0. Weighting spectrum: 300, 600, 1000, 2100 K. The KASHIL-E70 is a MATXS-format, 199-group neutron and 42-group photon cross section library for shielding applications based on ENDF/B-VII.0. The library contains 204 nuclide data including 8 thermal scattering law data processed by the NJOY99.259 code patched with NEA

  7. Direct thermal neutron capture

    We discuss the direct-capture theory pertaining to primary electric dipole (E1) transitions following slow-neutron capture. For light nuclides that we have studied (including 9Be, 12C, 13C, 24Mg, 25Mg, 26Mg, 32S, 33S, 34S, 40Ca, and 44Ca), estimates of direct-capture cross sections using optical-model potentials with physically realistic parameters, are in reasonable agreement with the data. Minor disagreements that exist are consistent with extrapolations to light nuclides of generally accepted formulations of compound-nucleus capture. We also discuss the channel-capture approximation which is, in general, a good representation of these cross sections in heavier nuclei particularly if the scattering lengths are not different from the corresponding potential radii. We also draw attention to cases where the use of this formula leads to inaccurate predictions. 9 refs., 1 fig., 2 tab

  8. Isotopic fractionation of Mg 2+(aq), Ca 2+(aq), and Fe 2+(aq) with carbonate minerals

    Rustad, James R.; Casey, William H.; Yin, Qing-Zhu; Bylaska, Eric J.; Felmy, Andrew R.; Bogatko, Stuart A.; Jackson, Virgil E.; Dixon, David A.

    2010-11-01

    Density-functional electronic structure calculations are used to compute the equilibrium constants for 26Mg/ 24Mg and 44Ca/ 40Ca isotope exchange between carbonate minerals and uncomplexed divalent aquo ions. The most reliable calculations at the B3LYP/6-311++G(2d,2p) level predict equilibrium constants K, reported as 10 3ln ( K) at 25 °C, of -5.3, -1.1, and +1.2 for 26Mg/ 24Mg exchange between calcite (CaCO 3), magnesite (MgCO 3), and dolomite (Ca 0.5Mg 0.5CO 3), respectively, and Mg 2+(aq), with positive values indicating enrichment of the heavy isotope in the mineral phase. For 44Ca/ 40Ca exchange between calcite and Ca 2+(aq) at 25 °C, the calculations predict values of +1.5 for Ca 2+(aq) in 6-fold coordination and +4.1 for Ca 2+(aq) in 7-fold coordination. We find that the reduced partition function ratios can be reliably computed from systems as small as M(CO)610- and M(HO)62+ embedded in a set of fixed atoms representing the second-shell (and greater) coordination environment. We find that the aqueous cluster representing the aquo ion is much more sensitive to improvements in the basis set than the calculations on the mineral systems, and that fractionation factors should be computed using the best possible basis set for the aquo complex, even if the reduced partition function ratio calculated with the same basis set is not available for the mineral system. The new calculations show that the previous discrepancies between theory and experiment for Fe 3+-hematite and Fe 2+-siderite fractionations arise from an insufficiently accurate reduced partition function ratio for the Fe 3+(aq) and Fe 2+(aq) species.

  9. Isotopic Fractionation of Mg2+(aq), Ca2+(aq), and Fe2+(aq) with Carbonate Minerals

    Rustad, James R.; Casey, William H.; Yin, Qing-Zhu; Bylaska, Eric J.; Felmy, Andrew R.; Bogatko, Stuart A.; Jackson, Virgil E.; Dixon, David A.

    2010-11-15

    Density functional electronic structure calculations are used to compute the equilibrium constant (the isotope fractionation factor) for 26Mg/24Mg and 44Ca/40Ca isotope exchange between carbonate minerals and uncomplexed divalent aquo ions. The most reliable calculations at the B3LYP/6-311++G(2d,2p) level predict equilibrium constants K, reported as 103ln(K) at 25 °C, of -5.3, -1.1, and +1.1 for 26Mg/24Mg exchange between calcite (CaCO3), magnesite (MgCO3), and dolomite (Ca0.5Mg0.5CO3), respectively, and Mg2+(aq), with positive values indicating enrichment in the mineral phase. For 44Ca/40Ca exchange between calcite and Ca2+(aq), the calculations predict values of +1.5 for Ca2+(aq) in six-fold coordination and +4.1 for Ca2+(aq) in seven-fold coordination. We find that the reduced partition function ratios can be reliably computed from systems as small as M(CO3)610- and M2+(H2O)6 embedded in a set of fixed atoms representing the 2nd shell (and greater) coordination environment. We find that the aqueous cluster representing the aquo ion is much more sensitive to improvements in the basis set than the calculations on the mineral systems, and that fractionation factors should be computed using 2 the best possible basis set for the aquo complex, even if the reduced partition function ratio calculated with the same basis set is not available for the mineral system. The new calculations show that the previous discrepancies between theory and experiment for Fe3+-hematite and Fe2+-siderite fractionations arise from an insufficiently accurate reduced partition function ratio for the Fe3+(aq) and Fe2+(aq) species.

  10. ZZ FSXJ32, MCNP nuclear data library based on JENDL-3.2. ZZ FSXLIBJ33, MCNP nuclear data library based on JENDL-3.3

    1 - Description of program or function: - NEA-1424/03: JENDL-3.2 based MCNP library. Format: MCNP. Number of groups: Continuous energy cross section library. Nuclides: H, He, Li, Be, B, C, N, O, F, Na, Mg, Al, Si, P, S, Cl, Ar, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Ga, Ge, As, Se, Br, Kr, Rb, Sr, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, In, Sn, Sb, Te, I, Xe, Cs, Ba, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Hf, Ta, W, Pb, Bi, Ra, Ac, Th, Pa, U, Np, Pu, Am, Cm, Bk, Cf, Es, Fm. Temperatures: 293 K, 600 K, 900 K, 1200 K, 1500 K, 2000 K. Origin: JENDL-3.2. The temperature-dependent continuous energy cross section library for MCNP, FSXJ32, was prepared from JENDL-3.2 for a variety of applications in the field of atomic energy. - NEA-1424/06: April 2005: This is the DVD version of ZZ-FSXJ32 NEA-1424/03. - NEA-1424/07: This version differs from version NEA-1424/05 in the following: Index files xsdir.fsxlb331 and xsdir.fsxlb332 have been updated, since atomic weights were missing for 23 nuclides. JENDL-3.3 based MCNP library. Format: MCNP. Number of groups: Continuous energy cross section library. Nuclides: 337 nuclides contained in JENDL-3.3. H-1, H-2, He-3, He-4, Li-6, Li-7, Be-9, B-10, B-11, C-Nat, N-14, N-15, O-16, F-19, Na-23, Mg-24, Mg-25, Mg-26, Al-27, Si-28, Si-29, Si-30, P-31, S-32, S-33, S-34, S-36, Cl-35, Cl-37, Ar-40, K-39, K-40, K-41, Ca-40, Ca-42, Ca-43, Ca-44, Ca-46, Ca-48, Sc-45, Ti-46, Ti-47, Ti-48, Ti-49, Ti-50, V-Nat, Cr-50, Cr-52, Cr-53, Cr-54, Mn-55, Fe-54, Fe-56, Fe-57, Fe-58, Co-59, Ni-58, Ni-60, Ni-61, Ni-62, Ni-64, Cu-63, Cu-65, Ga-69, Ga-71, Ge-70, Ge-72, Ge-73, Ge-74, Ge-76, As-75, Se-74, Se-76, Se-77, Se-78, Se-79, Se-80, Se-82, Br-79, Br-81, Kr-78, Kr-80, Kr-82, Kr-83, Kr-84, Kr-85, Kr-86, Rb-85, Rb-87, Sr-86, Sr-87, Sr-88, Sr-89, Sr-90, Y-89, Y-91, Zr-90, Zr-91, Zr-92, Zr-93, Zr-94, Zr-95, Zr-96, Nb-93, Nb-94, Nb-95, Mo-92, Mo-94, Mo-95, Mo-96, Mo-97, Mo-98, Mo-99, Mo-100, Tc-99, Ru-96, Ru-98, Ru-99, Ru-100, Ru-101, Ru-102, Ru-103, Ru-104, Ru-106, Rh

  11. Separation of stable isotopes of alkali and alkaline earth metals in chemical exchange systems with crown ethers

    Chemical isotope exchange in two-phase water - organic systems Men+ (water) - MeLn+ (org), where Me = Li, Ca, K, Mg; L = crown ethers with 5 to 6 oxygen atoms in macrocyclic ring; org = CHCl3, CH2Cl2 has been studied. The process of isotope separation has been realized by extraction chromatography. The chromatographic column contained a fixed aqueous phase. The organic solution of metal complex with crown ether was eluted through the column. On contact with the fixed aqueous phase in the course of chromatography, metal salt reextraction occurred and interphase isotope exchange between aqueous and organic phases resulted. Isotope separation factors in these systems were in the range of: 1.0032 - 1.020 (6Li/7Li), 1.0016 - 1.0038 (40Ca/44Ca), 1.0007 - 1.0011 (39K/41K), 1.0014 - 1.0044 (24Mg/26Mg). The theoretical model has been proposed to interpret the high separation factors in crown ether extraction systems. According to this model, the potential in such systems has a very flat bottom. This type of potential results in weakening the force field and decreasing of β-factor (i.e., (s/s')f) in spite of comparatively high energy of complexation. This model can interpret both high separation factors and their strong dependence on the type of crown ether. (author)

  12. The total cross sections of heavy ion reaction and the nuclear transfer

    The total reaction cross section of the systems 12C + 12C, 12C + 40Ca, 12C + 90Zr, 12C + 208Pb, 40Ca + 40Ca, 40Ca + 208Pb + 90Zr + 90Zr, 90Zr + 208Pb and 208Pb + 208Pb for a wide range of energies has been calculated microscopically. A WKB expression for the imaginary phase shift in the impact paremeter representation has been employed. The imaginary part of the optical potential has been constructed by using the first term of multiple scattering theory with the effect of Pauli blocking incorporated into it. The inclusion of the nuclear and Coulomb interactions is shown to be important. The theoretical results do not show very good agreement with the experimental data at lower energies. This is attributed to the weak absorption contained in the imaginary potential of the ''tοA οB'' interaction, wich contained only quasifree knock-out as the dominant reaction mechanism. (author)

  13. Chemical and Charge Imbalance Induced by Radionuclide Decay: Effects on Waste Form Structure

    Van Ginhoven, Renee M.; Jaffe, John E.; Jiang, Weilin; Strachan, Denis M.

    2011-04-01

    This is a milestone document covering the activities to validate theoretical calculations with experimental data for the effect of the decay of 90Sr to 90Zr on materials properties. This was done for a surragate waste form strontium titanate.

  14. The PSIMECX medium-energy neutron activation cross-section library. Part III: Calculational methods for heavy nuclei

    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: 12C, 13C, 16O, 17O, 18O, 23Na, 24Mg, 25Mg, 26Mg, 27Al, 28Si, 29Si, 30Si, 31P, 32S, 33S, 34S, 36S, 35Cl, 37Cl, 39K, 40K, 41K, 40Ca, 42Ca, 43Ca, 44Ca, 46Ca, 48Ca, 46Ti, 47Ti, 48Ti, 49Ti, 50Ti, 50V, 51V, 50Cr, 52Cr, 53Cr, 54Cr, 55Mn, 54Fe, 56Fe, 57Fe, 58Fe, 58Ni, 60Ni, 61Ni, 62Ni, 64Ni, 63Cu, 65Cu, 64Zn, 66Zn, 67Zn, 68Zn, 70Zn, 92Mo, 94Mo, 95Mo, 96Mo, 97Mo, 98Mo, 100Mo, 121Sb, 123Sb, 204Pb, 206Pb, 207Pb, 208Pb, 232Th and 238U. 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)

  15. The PSIMECX medium-energy neutron activation cross-section library. Part 1: Description and procedures for use

    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: 12C, 13C, 16O, 17O, 18O, 23Na, 24Mg, 25Mg, 26Mg, 27Al, 28Si, 29Si, 30Si, 31P, 32S, 33S, 34S, 36S, 35Cl, 37Cl, 39K, 40K, 41K, 40Ca, 42Ca, 43Ca, 44Ca, 46Ca, 48Ca, 46Ti, 47Ti, 48Ti, 49Ti, 50Ti, 50V, 51V, 50Cr, 52Cr, 53Cr, 54Cr, 55Mn, 54Fe, 56Fe, 57Fe, 58Fe, 58Ni, 60Ni, 61Ni, 62Ni, 64Ni, 63Cu, 65Cu, 64Zn, 66Zn, 67Zn, 68Zn, 70Zn, 92Mo, 94Mo, 95Mo, 96Mo, 97Mo, 98Mo, 100Mo, 121Sb, 123Sb, 204Pb, 206Pb, 207Pb, 208Pb, 232Th and 238U. 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 first report, from a set of three, describes the form and usage of the library; the other two reports document the calculational methods. The present organisation of the library is the author's first idea and adequate for the intended use (activation calculations); being machine readable, translation of the library into other formats is straightforward. (author)

  16. Treatment of competition between complete fusion and quasifission in collisions of heavy nuclei

    Adamian, G. G.; Antonenko, N.V.; Scheid, W.; Volkov, V. V.

    1997-01-01

    A model of competition between complete fusion and quasifission channels in fusion of two massive nuclei is extended to include the influence of dissipative effects on the dynamics of nuclear fusion. By using the multidimensional Kramers-type stationary solution of the Fokker-Planck equation, the fusion rate through the inner fusion barrier in mass asymmetry is studied. Fusion probabilities in symmetric 90Zr+90Zr, 100Mo+100Mo, 110Pd+110Pd, 136Xe+136Xe, almost symmetric 86Kr+136Xe and 110Pd+13...

  17. Improved Quantum Molecular Dynamics Model and its Application to Fusion Reaction Near Barrier

    2001-01-01

    An improved quantum molecular dynamics model is proposed. By using this model, the properties of ground state of nuclei from 6Li to 208Pb can be described very well with one set of parameters. The fusion reactions for 40Ca+90Zr, 40Ca+96Zr and 48Ca+90Zr at the energy near the barrier are studied by this model. The experimental data of the fusion cross sections for 40Ca+90,96Zr at the energy near the barrier can be reproduced remarkably well without introducing any new parameters. The mechanism

  18. Elastic and inelastic {alpha}-scattering cross-sections obtained with the 44 MeV fixed energy Saclay cyclotron on separated targets of {sup 24}Mg, {sup 25}Mg, {sup 26}Mg, {sup 40}Ca, {sup 46}Ti, {sup 48}Ti, {sup 50}Ti, {sup 52}Cr, {sup 54}Fe, {sup 56}Fe, {sup 58}Fe, {sup 58}Ni, {sup 60}Ni, {sup 62}Ni, {sup 64}Ni, {sup 63}Cu, {sup 65}Cu, {sup 64}Zn, {sup 112}Sn, {sup 114}Sn, {sup 116}Sn, {sup 118}Sn, {sup 120}Sn, {sup 122}Sn, {sup 124}Sn and {sup 208}Pb using the Saclay fixed-energy cyclotron; Sections efficaces differentielles elastiques et inelastiques obtenues par diffusion de particules {alpha} de 44 MeV sur des cibles de {sup 24}Mg, {sup 25}Mg, {sup 26}Mg, {sup 40}Ca, {sup 46}Ti, {sup 48}Ti, {sup 50}Ti, {sup 52}Cr, {sup 54}Fe, {sup 56}Fe, {sup 58}Fe, {sup 58}Ni, {sup 60}Ni, {sup 62}Ni, {sup 64}Ni, {sup 63}Cu, {sup 65}Cu, {sup 64}Zn, {sup 112}Sn, {sup 114}Sn, {sup 116}Sn, {sup 118}Sn, {sup 120}Sn, {sup 122}Sn, {sup 124}Sn et {sup 208}Pb au cyclotron a energie fixe de saclay

    Bruge, G. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires. Departement de physique nucleaire, service de physique nucleaire a moyenne energie

    1967-01-01

    This report contains elastic and inelastic {alpha}-scattering cross-sections obtained with the 44 MeV fixed energy Saclay cyclotron on Mg, Ca, Ti, Cr, Fe, Ni, Co, Zn, Sn and Pb enriched targets. (author) [French] Ce rapport contient les tableaux des sections efficaces differentielles obtenues par diffusion elastique et inelastique des particules {alpha} de 44 MeV, fournies par le cyclotron a energie fixe de Saclay, sur des cibles d'isotopes separes de Mg, Ca, Ti, Cr, Fe, Ni, Co, Zn, Sn et Pb. (auteur)

  19. 87Sr(d,p)88Sr at 18 MeV and the 1g9/22d5/2 multiplet

    Differential cross sections for 87Sr(d,p)88Sr transitions to the particle-hole states of 88Sr were obtained with the Pittsburgh 18 MeV deuteron beam and the Enge split-pole spectrography. States of 88Sr up to 7223 keV in excitation were studied with a total resolution of 16 keV. Finite-range and zero-range DWBA predictions were found to be in excellent agreement with each other and also in acceptable agreement with the data. For eleven levels, mixed l=2 and l=0 transitions were identified. Residual interaction matrix elements for the (1g-19/22d5/2) multiplet were derived from the 88Sr data. Two potentially divergent results of 91Zr(p,d)90Zr and 91Zr(3He,α)90Zr reactions for the (1g-19/22d5/2) multiplet in 90Zr can be reconciled by allowing for ln mixing. The revised 90Zr matrix elements are compared with the 88Sr result. (orig.)

  20. Local covariant density functional constrained by the relativistic Hartree-Fock theory

    Liang, H Z; Ring, P; Roca-Maza, X; Zhao, P W; 10.1063/1.4764245

    2012-01-01

    The recent progress in the localized covariant density functional constrained by the relativistic Hartree-Fock theory is briefly presented by taking the Gamow-Teller resonance in 90Zr as an example. It is shown that the constraints introduced by the Fock terms into the particle-hole residual interactions are straight forward and robust.

  1. Decay Properties Of The Dipole Isobaric Analog Resonances

    Gorelik, M L; Urin, M H

    2006-01-01

    A continuum-RPA-based approach is applied to describe the decay properties of isolated dipole isobaric analog resonances in nuclei having not-too-large neutron excess. Calculated for a few resonances in 90Zr the elastic E1-radiative width and partial proton widths for decay into one-hole states of 89Y are compared with available experimental data.

  2. Optical model studies of 6Li elastic scattering at 156 MeV

    Differential cross sections for 6Li elastic scattering at 156 MeV from 12C, 40Ca 90Zr and 208Pb are presented. The sensitivity to various potential forms is established by using Saxon Woods, Saxon-Woods-squred, density independent and density dependent folded potentials. The extent to which the experimental data determine the potentials and related quantities is discussed. (orig.)

  3. Controlling factors of Ca isotope fractionation in scleractinian corals evaluated by temperature, pH and light controlled culture experiments

    Inoue, Mayuri; Gussone, Nikolaus; Koga, Yasuko; Iwase, Akihiro; Suzuki, Atsushi; Sakai, Kazuhiko; Kawahata, Hodaka

    2015-10-01

    In this study, the 44Ca/40Ca ratios of Porites australiensis grown under three different culture experiments composed of temperature, pH and light controlled culture experiments are measured. The temperature dependent isotope fractionation of 0.02‰/°C deduced from this study is similar to inorganic aragonite, but the degree of isotope fractionation is about +0.4‰ offset in corals. These observations agree with earlier results on different coral species, suggesting Ca isotope fractionation during Ca transmembrane transport in corals. While in cultured corals a significant temperature dependence of δ44Ca is observed, the relationships between calcium isotope fractionation and pH as well as light intensity are negligible. Therefore variation of δ44Ca in Porites corals is mainly controlled by temperature. A combination of δ44Ca and Sr/Ca of corals in temperature controlled experiments cannot be explained by Rayleigh type fractionation directly from a fluid, which is seawater-like in terms of δ44Ca and Sr/Ca. Through coral-specific biomineralization processes, overall mean δ44Ca of scleractinian corals including previous studies are different from biogenic aragonites secreted by sclerosponges and pteropods, but are comparable with those of bivalves as well as calcitic coccolithophores and foraminifers. These findings are important for better understanding biomineralization in corals and in order to constrain the Ca isotopic composition of oceanic Ca sinks in response to climate changes and associated with shifts of calcite and aragonite seas.

  4. The giant dipole resonance at high spin and moderate temperature

    The role of deformation, temperature and angular momentum in the evolution of the isovector giant dipole resonance (GDR) with excitation energy is studied. The dipole cross section is calculated applying a cranked Nilsson potential together with a separable dipole-dipole force. Calculations for 90Zr, 108Sn and 164Er are presented. For the last two nuclides, 108Sn and 164Er, the observed development of the damping width of the dipole intensity is explained by the evolution of the equilibrium deformation. 90Zr remains spherical at the E* studied, the thermal shape fluctuations being responsible of the broadening of the cross section. The effect of fluctuations on the angular distribution of the gamma-rays associated with the dipole emission, strongly depends on the free energy surface shape. (orig.)

  5. Communication of nuclear data progress: No.15 (1996)

    Communication of Nuclear Data Progress (CNDP) is set up by Chinese Nuclear DATA Center. This is the 15th issue. The nuclear data achievements and progress in China during the last year are presented. It mainly includes: the measurements of the energy spectrum and angular distributions of protons from stainless steel bombarded by 14.6 MeV neutrons, theoretical calculations of 59Co and 90Zr neutron reaction data, the method and program CABEI for adjusting consistency between natural and its isotope data, 58,60,61,62,64,NatNi(n, p), 59Co, 90Zr(n,x) and 84Rb decay data, the status of CENDL-2.1 and progress on Chinese Evaluated Nuclear Parameter Library

  6. In-plane Isotropic Microwave Performance of CoZr Trilayer in GHz Range

    Pan, Lulu; Wang, Fenglong; Wang, Wenfeng; Chai, Guozhi; Xue, Desheng

    2016-02-01

    In this paper, we investigate the high frequency performance of Co90Zr10/SiO2/Co90Zr10 trilayers. It is demonstrated that the in-plane isotropic microwave performance is theoretically derived from the solution of the Landau-Lifshitz-Gilbert equation and experimentally achieved in that sandwich structured film. The valuable isotropic behavior comes from the superposition of two uncouple ferromagnetic layers in which the uniaxial magnetic anisotropic fields are equivalent but mutually orthogonal. Moreover, the isotropic microwave performance can be tuned to higher resonance frequency up to 5.3 GHz by employing the oblique deposition technique. It offers a convenient and effective way to achieve an unusual in-plane isotropic microwave performance with high permeability in GHz, holding promising applications for the magnetic devices in the high frequency information technology.

  7. Contribution to the spectroscopy of 50 neutron isotones

    Proton states in the isotones N = 50 have been studied through the reaction (3He,d) on 88Sr, 90Zr and 92Mo target nuclei with 18 MeV 3He projectiles and also neutron hole states using the (3He,α) reaction on the same target. The information thus obtained on independent quasi-particle or hole states completes the set of experimental data required for a microscopic description of the collective properties of the even isotones 88Sr, 90Zr and 92Mo in the framework of BCS(IGE) + RPA theories. The results of this calculation are compared to experimental data and, more particularly, the results of 20 MeV proton inelastic scattering on 88Sr are analysed using anti-symmetrized DWBA with the microscopic wave functions calculated previously. (author)

  8. Structural and ferroelectric properties of lanthanum modified BPZT ceramics

    Lanthanum modified Ba0.80Pb0.20Ti0.90Zr0.10O3 (BPZT) ceramics with composition Ba0.80-xLax Pb0.20Ti0.90Zr0.10O3; x = 0-0.01 in steps of 0.0025 were prepared by conventional solid state method. All the samples were sintered at 1325 deg. C after compacting in circular discs. Detailed structural and ferroelectric properties were carried out for sintered specimens. X-ray diffraction analysis for all the sintered specimens shows tetragonal structure with perovskite. Coercive field (Ec) and remanent polarization (Pr) to spontaneous polarization (Ps) ratio (Pr/Ps) was found to decrease with increase in temperature. Pr/Ps ratio was found to decrease with increase in x, except x = 0.0025.

  9. Microscopic calculation of total ordinary muon capture rates for medium-weight and heavy nuclei

    Total ordinary muon capture (OMC) rates are calculated on the basis of the quasiparticle random phase approximation for several spherical nuclei from 90Zr to 208Pb. It is shown that total OMC rates calculated with the free value of the axial-vector coupling constant gA agree well with the experimental data for medium-size nuclei and considerably exceed the experimental rates for heavy nuclei. The sensitivity of theoretical OMC rates to the nuclear residual interactions is discussed. (author)

  10. Calculations of the isoscalar giant monopole resonance within the self-consistent RPA and its extensions

    Tselyaev, V; Litvinova, E; Speth, J

    2009-01-01

    The strength distributions of the isoscalar giant monopole resonance have been calculated in $^{16}$O, $^{40}$Ca, $^{90}$Zr, $^{112-124}$Sn, $^{144}$Sm, and $^{208}$Pb nuclei within the self-consistent random phase approximation and its extensions which include pairing correlations and quasiparticle-phonon coupling. The results are compared with the available experimental data. The problem of the nuclear matter incompressibility is discussed.

  11. Charge independence and charge symmetry breaking interactions and the Coulomb energy anomaly in isobaric analog states

    Effects of CIB (charge independence breaking) and CSB (charge symmetry breaking) interactions on the Coulomb displacement energies of isobaric analog states are investigated for 48Ca, 90Zr and 208Pb. Mass number dependence of the Coulomb energy anomalies is well explained when CIB and CSB interactions are used which reproduce the differences of the scattering lengths as well as those of the effective ranges of low energy nucleon-nucleon scattering. (author) 17 refs., 3 figs., 3 tabs

  12. Enhanced population of side band of {sup 155}Gd in heavy-ion Coulomb excitation

    Oshima, Masumi; Hayakawa, Takehito; Hatsukawa, Yuichi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment] [and others

    1998-03-01

    In the Coulomb excitation of {sup 155}Gd with heavy projectiles, {sup 32}S, {sup 58}Ni and {sup 90}Zr, unexpectedly large enhancement of a positive-parity side band has been observed. This enhancement could not be reproduced by a Coulomb-excitation calculation taking into account the recommended upper limits of E1 or E3 transitions, which are compiled in the whole mass region, and is proportional to the electric field accomplished in the Coulomb-scattering process. (author)

  13. Calculations of Compound Nucleus Spin-Parity Distributions Populated via the (p,t) Reaction in Support of Surrogate Neutron Capture Measurements

    Benstead, J.; Tostevin, J. A.; Escher, J. E.; Burke, J. T.; Hughes, R. O.; Ota, S.; Casperson, R. J.; Thompson, I. J.

    2016-06-01

    The surrogate reaction method may be used to determine the cross section for neutron induced reactions not accessible through standard experimental techniques. This is achieved by creating the same compound nucleus as would be expected in the desired reaction, but through a different incident channel, generally a direct transfer reaction. So far, the surrogate technique has been applied with reasonable success to determine the fission cross section for a number of actinides, but has been less successful when applied to other reactions, e.g. neutron capture, due to a `spin-parity mismatch'. This mismatch, between the spin and parity distributions of the excited levels of the compound nucleus populated in the desired and surrogate channels, leads to differing decay probabilities and hence reduces the validity of using the surrogate method to infer the cross section in the desired channel. A greater theoretical understanding of the expected distribution of levels excited in both the desired and surrogate channels is therefore required in order to attempt to address this mismatch and allow the method to be utilised with greater confidence. Two neutron transfer reactions, e.g. (p,t), which allow the technique to be utilised for isotopes further removed from the line of stability, are the subject of this study. Results are presented for the calculated distribution of compound nucleus states populated in 90Zr, via the 90Zr(p,t)90Zr reaction, and are compared against measured data at an incident proton energy of 28.56 MeV.

  14. ZZ IRDF-2002, 640-Group Cross-Section Library and Spectra for Dosimetry Calculation in ENDF-6 Format. ZZ IRDF-2002-ACE, Cross-Section Library and Spectra for Dosimetry Calculation in ACE Format for Monte Carlo methods. ZZ IRDF-90, 640-Group Cross-Section Library and Spectra for Dosimetry Calculation in ENDF-6 Format. ZZ IRDF-82, 620-Group Cross-Section Library and Spectra for Dosimetry Calculation in ENDF-5 Format

    sections, using the SAND-II group structure. (2) The reactions 19F(n,2n), 24Mg(n,p), 31P(n,p), 29Cu(n,2n), 64Zn(n,p), 90Zr(n,2n), 93Nb(n,n') and 103(Rh(n,n'), supplied by Vonach. This data was converted to the ENDF/B-V Format, which in turn was converted to 620 group form. (3) The reaction 23Na(n,2n) provided by Marcinkowski. This data was converted to the ENDF/B-V Format (5) and then converted to 620 group Format. (4) The reaction 241Am(n,f) as supplied by Patrick. This data was converted to the ENDF/B-V Format at Stuttgart and then converted to 620 group form. (5) ASTM and EUR standards damage Cross sections for iron as provided by Zijp (10) in the form of 620 group Cross sections. This data was converted to the ENDF/B-V Format. II) The Benchmark Spectra library contains ten benchmark spectra, including: (1) The NBS 252Cf spontaneous fission; the NBS 235U and ENDF/B-V 235U thermal fission, the Intermediate-Energy Standard Neutron Field (ISNF), the Coupled Fast Reactivity Measurement Facility (CFRMF), the 10 % Enriched Uranium Cylindrical Critical Assembly (BIG-TEN) and the Coupled Thermal/Fast Uranium and Boron Carbide Spherical Assembly (SIGMA-SIGMA) spectra, all of which were provided by Eisenhauer in 620 group form. (2) The ORR and YAYOI Spectra, which were provided by Greenwood in 100 group form. (3) The Central Zone Flux of the NEACRP Benchmark Spectra provided by Goel in 208 group form. - (B) ZZ-IRDF-90: The following changes compared to the 1982 version should be noted: - IRDF-90 is mainly based on the ENDF/B-IV data and its present version contains cross section values for 51 different dosimetry reactions. Damage Cross sections are given for three different materials: Fe, Cr, Ni. - The library is written in the ENDF-6 Format. - Gas production reactions are completely missing from IRDF-90.V.1 and other important dosimetry reactions are also not yet present. At the same time, double cross section information is given for the following reactions Ni582, Cu632 and Fe

  15. Biological and ecological insights into Ca isotopes in planktic foraminifers as a palaeotemperature proxy

    Kasemann, Simone A.; Schmidt, Daniela N.; Pearson, Paul N.; Hawkesworth, Chris J.

    2008-07-01

    Sea surface temperature (SST) is a critical variable in the Earth's climate system since it influences atmospheric circulation, the hydrological cycle and, via ocean surface density, drives ocean circulation. A detailed reconstruction of past SST's is therefore a central goal of palaeoceanographic studies. Although calcium isotopes in foraminiferal carbonate have been introduced as a new proxy for SST reconstruction, there is considerable debate about their robustness and general applicability. To resolve some of these questions, we have investigated the extent to which other environmental parameters e.g. the calcification temperature, depth stratification, growth rates and/or environmental adaptation may influence the δ44Ca values of planktic foraminifers in modern and Eocene samples. Geographically distributed data sets are affected by the exchange of cryptic species, i.e. morphologically similar but genetically distinct species, and by a mixing of optimal versus less optimal adaptation. Thus, we have compared species within individual samples to evaluate whether the well documented depth stratification of foraminifers is reflected in their calcium isotopes. The Eocene data set shows a general agreement between δ44Ca and δ18O-derived calcification temperatures which supports a temperature effect on Ca isotope incorporation. The vertical temperature gradient using the different depth habitats of several foraminiferal species indicates a δ44Ca temperature dependence of ~ 0.034‰ °C - 1 similar to inorganic calcite (0.015‰ °C - 1 ) and cultured O. universa (0.019‰ °C - 1 ). The gradient resembles the global sediment δ44Ca compilation, but it is significantly smaller than the temperature calibration of 0.22 ± 0.02‰ °C - 1 for cultured G. sacculifer. The modern data set shows a general correlation between δ44Ca and depth habitat reflecting a similar temperature gradient to the Eocene sample set. In contrast, the lower absolute δ44Ca values for the

  16. Cyclotron production of {sup 44}Sc for clinical application

    Krajewski, S.; Bilewicz, A. [Institute of Nuclear Chemistry and Technology, Warsaw (Poland); Cydzik, I. [Institute of Nuclear Chemistry and Technology, Warsaw (Poland); European Commission Joint Research Center, Ispra (Italy). Inst. for Health and Consumer Protection; Warsaw Univ. (Poland). Heavy Ion Lab.; Abbas, K. [European Commission Joint Research Center, Ispra (Italy). Institute for Transuranium Elements; Bulgheroni, A.; Simonelli, F.; Holzwarth, U. [European Commission Joint Research Center, Ispra (Italy). Inst. for Health and Consumer Protection

    2013-08-01

    {sup 44} is a promising {beta}{sup +}-emitter for molecular imaging with intermediate half-life of 4 h. Due to the chemical similarity of Sc{sup 3+} to the Lu{sup 3+} and Y{sup 3+} cations, {sup 44}Sc-DOTA bioconjugates are expected to demonstrate similar properties in vivo as the {sup 177}Lu- and {sup 90}Y-bioconjugates, what is important in planning the radionuclide therapy. {sup 44}Sc can be obtained from the {sup 44}Ti/{sup 44}Sc generator. An alternative method for {sup 44}Sc production can be the irradiation of {sup 44}Ca target at small cyclotrons. The aim of our work was to optimize the parameters of {sup 44}CaCO{sub 3} irradiation and to develop a simple procedure for {sup 44}Sc separation from the calcium target. For optimization study, {sup 44}CaCO{sub 3} targets were irradiated by protons in the energy range of 5.6-17.5 MeV with 9 MeV being found to be the best energy for {sup 44}Ca irradiations. A simple and fast separation procedure of {sup 44}Sc from calcium target was developed using chelating resin Chelex 100. DOTATATE conjugate was successfully radiolabelled with high yield at elevated temperature using the produced {sup 44}Sc. While {sup 44}CaCO{sub 3} is relatively expensive, the cost of {sup 44}Sc-DOTATATE production can be reduced by target recovery. Due to low proton energy required to produce GBq activity level of {sup 44}Sc, the availability of {sup 44}Sc radioisotope could be enhanced to open new opportunities for applications in medical imaging. (orig.)

  17. Cyclotron production of 44Sc for clinical application

    44 is a promising β+-emitter for molecular imaging with intermediate half-life of 4 h. Due to the chemical similarity of Sc3+ to the Lu3+ and Y3+ cations, 44Sc-DOTA bioconjugates are expected to demonstrate similar properties in vivo as the 177Lu- and 90Y-bioconjugates, what is important in planning the radionuclide therapy. 44Sc can be obtained from the 44Ti/44Sc generator. An alternative method for 44Sc production can be the irradiation of 44Ca target at small cyclotrons. The aim of our work was to optimize the parameters of 44CaCO3 irradiation and to develop a simple procedure for 44Sc separation from the calcium target. For optimization study, 44CaCO3 targets were irradiated by protons in the energy range of 5.6-17.5 MeV with 9 MeV being found to be the best energy for 44Ca irradiations. A simple and fast separation procedure of 44Sc from calcium target was developed using chelating resin Chelex 100. DOTATATE conjugate was successfully radiolabelled with high yield at elevated temperature using the produced 44Sc. While 44CaCO3 is relatively expensive, the cost of 44Sc-DOTATATE production can be reduced by target recovery. Due to low proton energy required to produce GBq activity level of 44Sc, the availability of 44Sc radioisotope could be enhanced to open new opportunities for applications in medical imaging. (orig.)

  18. Influences of calcium availability and tree species on Ca isotope fractionation in soil and vegetation

    Page, B.D.; Bullen, T.D.; Mitchell, M.J.

    2008-01-01

    The calcium (Ca) isotope system is potentially of great use for understanding biogeochemical processes at multiple scales in forest ecosystems, yet remains largely unexplored for this purpose. In order to further our understanding of Ca behavior in forests, we examined two nearly adjacent hardwood-dominated catchments with differing soil Ca concentrations, developed from crystalline bedrock, to determine the variability of 44Ca/ 40Ca ratios (expressed as ??44Ca) within soil and vegetation pools. For both sugar maple and American beech, the Ca isotope compositions of the measured roots and calculated bulk trees were considerably lighter than those of soil pools at these sites, suggesting that the trees were able to preferentially take up light Ca at the root-soil interface. The Ca isotope compositions of three of four root samples were among the lightest values yet reported for terrestrial materials (??44Ca ???-3.95???). Our results further indicate that Ca isotopes were fractionated along the transpiration streams of both tree species with roots having the least ??44Ca values and leaf litter the greatest. An approximately 2??? difference in ??44Ca values between roots and leaf litter of both tree species suggests a persistent fractionation mechanism along the transpiration stream, likely related to Ca binding in wood tissue coupled with internal ion exchange. Finally, our data indicate that differing tree species demand for Ca and soil Ca concentrations together may influence Ca isotope distribution within the trees. Inter-catchment differences in Ca isotope distributions in soils and trees were minor, indicating that the results of our study may have broad transferability to studies of forest ecosystems in catchments developed on crystalline substrates elsewhere. ?? 2008 Springer Science+Business Media B.V.

  19. Optical and structural characterization of SrZr{sub 0,1}Ti{sub 0,9}O{sub 3}

    Delgado-Nino, Pilar [Laboratorio de Catalisis Heterogenea, Departamento de Quimica, Facultad de Ciencias, Universidad Nacional de Colombia, Bogota, D.C. (Colombia); Lopez-Rivera, S.A., E-mail: adan@ula.ve [Grupo de Fisica Aplicada, Facultad de Ciencias, Universidad de los Andes, Merida (Venezuela, Bolivarian Republic of); Mestres-Vila, Lourdes; Martinez-Sarrion, Maria Luisa [Departamento de Quimica Inorganica, Facultad de Quimica, Universitat de Barcelona, Barcelona, Espana (Spain); Valencia-Rios, Jesus S. [Laboratorio de Catalisis Heterogenea, Departamento de Quimica, Facultad de Ciencias, Universidad Nacional de Colombia, Bogota, D.C. (Colombia)

    2012-10-15

    In this work, the ceramic compound SrTi{sub 0.90}Zr{sub 0,1}O{sub 3} (SZT) was synthesized by the citrate method. This solid showed a 12 nm crystallite size, reflecting the high degree of crystallinity obtained by this synthesis route. Differential and gravimetric thermal analysis showed that the solid was formed from 520 Degree-Sign C; the chemical composition was determined by ICP-AES4, giving a stoichiometry corresponding to the SrTi{sub 0.90}Zr{sub 0.10}O{sub 3} formula, and proved to be compatible with the X-ray diffraction data, refined by the Rietveld method. The morphology was explored by means of SEM and TEM, finding a homogenous particles distribution, arranged in lumps, susceptible to density changes by sintering between 1000 Degree-Sign C and 1200 Degree-Sign C. The photoluminescence (PL) spectrum shows a band between 470 nm and 520 nm, corresponding to the Ti and Zr ions 3d electronic transition. The SZT crystal structure is tetragonal with space group I4/mcm, number (140). - Highlights: Black-Right-Pointing-Pointer The ceramic nano structured compound SrTi{sub 0.90}Zr{sub 0,1}O{sub 3} was synthesized by the citrate method. Black-Right-Pointing-Pointer Differential and gravimetric thermal analysis showed the right thermodynamical parameters Black-Right-Pointing-Pointer Good agreement between the crystal structure, group theory and the optical properties was obtained. Black-Right-Pointing-Pointer The sized and high crystallinity of the nanoparticules was confirmed by SEM and TEM. Black-Right-Pointing-Pointer Crystal structure is tetragonal with space group I4/mcm was found by X-ray and Rietveld refinement.

  20. Alpha decay of {sup 181}Pb

    Davids, C.N.; Henderson, D.J.; Hermann, R. [and others

    1995-08-01

    The {alpha}-decay energy of {sup 181}Pb was measured as 7211(10) keV and 7044(15). In the first study the isotope was produced in {sup 90}Zr bombardments of {sup 94}Mo and, after traversing a velocity filter, implanted in a position-sensitive Si detector; no half life for {sup 181}Pb was reported. In the second study the isotope was produced in {sup 40}Ca bombardments of {sup 144}Sm and transported to a position in front of a Si(Au) surface barrier detector with a fast He-gas-jet capillary system; an estimate of 50 ms was determined for the {sup 181}Pb half life. Recently we investigated {sup 181}Pb {alpha} decay at ATLAS as part of a survey experiment in which a l-pnA beam of 400-MeV {sup 92}Mo was used to irradiate targets of {sup 89}Y, {sup 90,92,94}Zr, and {sup 92}Mo to examine yields for one- and two-nucleon evaporation products from symmetric cold-fusion reactions. Recoiling nuclei of interest were passed through the Fragment Mass Analyzer and implanted in a double-sided silicon strip detector for {alpha}-particle assay. With the {sup 90}Zr target we observed a group at 7065(20) keV which was correlated with A = 181 recoils and had a half life of 45(20) ms. Our new results for {sup 181}Pb therefore agreed with those of the second study. There was no indication in the {sup 90}Zr + {sup 92}Mo data of the 7211(10)-keV {alpha} particles seen by Keller et al. The interested reader is referred to the 1993 atomic mass evaluation wherein the input {alpha}-decay energies and resultant masses of the light Pb isotopes (including {sup 181}Pb) are discussed.

  1. Role of projectile breakup effects and intrinsic degrees of freedom on fusion dynamics

    Singh Gautam, Manjeet

    2016-05-01

    This article analyzes the fusion dynamics of loosely bound and stable projectiles with Zr-target isotopes within the context of the coupled channel approach and the energy-dependent Woods-Saxon potential model (EDWSP model). In the case of the 28Si + 90Zr reaction, the coupling to the inelastic surface excitations results in an adequate description of the observed fusion dynamics while in case of the 28Si + 94Zr reaction, the coupling to collective surface vibrational states as well as the neutron (multi-neutron) transfer channel is necessary in the coupled channel calculations to reproduce the below-barrier fusion data. However, the EDWSP model calculation provides an accurate explanation of the fusion data of 28Si + 90,94Zr reactions in the domain of the Coulomb barrier. In the fusion of the 6Li + 90Zr reaction, the inclusion of the nuclear structure degrees of freedom recovers the observed sub-barrier fusion enhancement but results in suppression of the above barrier fusion data by 34% with respect to the coupled channel calculations. Using EDWSP model calculations, this suppression factor is reduced by 14% and consequently, the above-barrier fusion data of 6Li + 90Zr reaction is suppressed by 20% with reference to the EDWSP model calculations. Such fusion suppression at above-barrier energies can be correlated with the breakup of the projectile (6Li) before reaching the fusion barrier, as a consequence of low binding energy. Supported by Dr. D. S. Kothari Post-Doctoral Fellowship Scheme sponsored by University Grants Commission (UGC), New Delhi, India

  2. Scattering of intermediate energy protons

    The scattering of 1 GeV protons appears to be a powerful means of investigating nuclear matter. We worked with SPESI and the formalism of Kerman-Mc Manus and Thaler. The amplitude of nucleon-nucleon scattering was studied as were the aspects of 1 GeV proton scattering (multiple scattering, absorption, spin-orbit coupling, N-N amplitude, KMT-Glauber comparison, second order effects). The results of proton scattering on 16O, the isotopes of calcium, 58Ni, 90Zr and 208Pb are given

  3. Low-energy enhancement of magnetic dipole radiation

    Schwengner, R.; Frauendorf, S.; Larsen, A.C.

    2013-01-01

    Magnetic dipole strength functions have been deduced from averages of a large number of $M1$ transition strengths calculated within the shell model for the nuclides $^{90}$Zr, $^{94}$Mo, $^{95}$Mo, and $^{96}$Mo. An enhancement of $M1$ strength toward low transition energy has been found for all nuclides considered. Large $M1$ strengths appear for transitions between close-lying states with configurations including proton as well as neutron high-$j$ orbits that re-couple their spins and add u...

  4. Cross section measurement for reaction 193Ir(n,2n)192m2Ir at 14.7 MeV

    The cross sections induced by neutron on long-lived radionuclides of importance in fusion reactor technology are measured by activation method for 193Ir(n,2n)192m2Ir reaction at 14.7 MeV. The neutron fluences are determined by the cross section of 93Nb(n,2n)92mNb. The neutron energies in these measurements are determined by cross section ratios for 90Zr(n,2n)89Zr and 93Nb(n,2n)92mNb reactions. (2 tabs.)

  5. Calculation of 90Sr content in food

    The method presented was used to determine the 90Sr contamination of the samples from the agricultural products and foods under investigation by measuring the Sr fractions in two different time settings. Considering the decays from 89Kr to 89Y and from 90Kr to 90Zr as well as the respective half-lives, the activity sums of the 89Sr and 90Sr with significantly differing half-lives are used for the calculations. The resulting 90Sr/89Sr activity ratio of the sample shows the contamination life, too. A correction is needed for the equilibrium activity sum of 90Sr+90Y. (Sz.J.)

  6. Isotopic dependence of the giant monopole resonance in the even-A ^{112-124}Sn isotopes and the asymmetry term in nuclear incompressibility

    Li, T; Liu, Y; Marks, R; Nayak, B K; Rao, P V Madhusudhana; Fujiwara, M; Hashimoto, H; Kawase, K; Nakanishi, K; Okumura, S; Yosoi, M; Itoh, M; Ichikawa, M; Matsuo, R; Terazano, T; Uchida, M; Kawabata, T; Akimune, H; Iwao, Y; Murakami, T; Sakaguchi, H; Terashima, S; Yasuda, Y; Zenihiro, J; Harakeh, M N

    2007-01-01

    The strength distributions of the giant monopole resonance (GMR) have been measured in the even-A Sn isotopes (A=112--124) with inelastic scattering of 400-MeV $\\alpha$ particles in the angular range $0^\\circ$--$8.5^\\circ$. We find that the experimentally-observed GMR energies of the Sn isotopes are lower than the values predicted by theoretical calculations that reproduce the GMR energies in $^{208}$Pb and $^{90}$Zr very well. From the GMR data, a value of $K_{\\tau} = -550 \\pm 100$ MeV is obtained for the asymmetry-term in the nuclear incompressibility.

  7. Effects of relativistic kinematics in heavy ion elastic scattering

    Relativistic corrections to the reaction kinematic parameters were made for elastic scattering of 6Li, 12C and 40Ar from 40Ca, 90Zr and 208Pb targets at incident energies between 20 and 100 MeV/nucleon. The results of optical model calculations show that the effects of such corrections are important when describing the angular distributions of elastic scattering cross sections for heavy ion scattering at incident energies as low as around 40 MeV/nucleon. The effects on the total reaction cross sections on the other hand, were found to be small within the energy range studied when the optical model potential is fixed. (authors)

  8. Semiclassical distorted wave model analysis of inclusive (N, N'x) reactions for incident energies up to 400 MeV

    The semiclassical distorted wave (SCDW) model with the Wigner transform of a one-body density matrix is applied to analyses of multistep direct processes in (p, p'x) reactions on 12C, 90Zr, and 197Au at incident energies near 150 MeV, and 392 MeV (p, p'x) and 346 MeV (p, nx) reactions on 40Ca. The calculations show good agreement with experimental double-differential cross sections over a wide mass range of target nuclei, except at backward angles. (author)

  9. Beta decay studies of r-process nuclei at the National Superconducting Cyclotron Laboratory

    Pereira, J; Arndt, O; Becerril, A; Elliot, T; Estrade, A; Galaviz, D; Hennrich, S; Hosmer, P; Kessler, R; Kratz, K L; Lorusso, G; Mantica, P F; Matos, M; Montes, F; Santi, P; Pfeiffer, B; Quinn, M; Schatz, H; Schertz, F; Schnorrenberger, L; Smith, E; Tomlin, B E; Walters, W; Wöhr, A

    2009-01-01

    The impact of nuclear physics on astrophysical r-process models is discussed, emphasizing the importance of beta-decay properties of neutron-rich nuclei. Several r-process motivated beta-decay experiments performed at the National Superconducting Cyclotron Laboratory are presented. The experiments include the measurement of beta-decay half-lives and neutron emission probabilities of nuclei in regions around Ni-78; Se-90; Zr-106 and Rh-120, as well as spectroscopic studies of Pd-120. A summary on the different experimental techniques employed, data analysis, results and impact on model calculations is presented.

  10. Dielectric behaviour of Pb-substituted BZT ceramics

    Parveen Kumar; Sangeeta Singh; J K Juneja; K K Raina; Chandra Prakash

    2011-12-01

    Material series with compositional formula Ba1.0–PbTi0.90Zr0.10O3 (0 ≤ ≤ 0.20, in steps of 0.05) were prepared by conventional solid state method. All the samples were subjected to X-ray diffraction (XRD) studies and found to be single phase with perovskite structure. SEM measurements were done in order to collect micro-structural information. Different transition temperatures were found to depend on the Pb content. Tetragonality (/) and Curie temperature (c) increase with increase in lead content . Dielectric properties were studied as a function of temperature and frequencies.

  11. Isovector excitations of N ≠ Z nuclei

    We show that the method based on the tensor coupling of an appropriate family of isovector excitation operators to the parent isospin multiplet can be used, to advantage, for the correct treatment of the isospin degree of freedom in non isoscalar nuclei. This method is applicable to any isovector excitation operator and for parent states which need not to be of the closed subshells type. As an illustration we apply it to the study of the Gamow-Teller transition strength in 90Zr. (author)

  12. A mechanism for excitation of metastable levels by(γ,γ') reactions

    The analysis of the cross-section of 77Se and 87Sr isomeric states excitation in the (γ, γ') reaction, was carried out using neutron pick-up and stripping reaction results. It allows the shell configurations of the transitions to the activation states to be determined. To check thus obtained conclusions the energies of Jπ=1- excited states for 90Zr and 138Ba were calculated, which are in good agreement with the resonance structure at the γ-quanta elastic scattering in the 5 to 10 MeV energy range

  13. Description of Tsub(>) giant resonances in spherical nuclei

    The formulae for calculating the energies and B(EE1) probabilities of the Tsub(>) giant resonances are derived within the quasiparticle-phonon nuclear model. The characteristics of the giant dipole resonances are calculated in several spherical nuclei and a correct position of the Tsub() collective 1- states is obtained. The calculated cross section ratios deltasub(-1)(Tsub(>))/deltasub(-1)(Tsub(88Sr, 90Zr, 92Mo and are three times as large as the experimental values for sup(116, 120, 124)Sn. The decrease in the cross sections deltasub(-1)(Tsub(>)) in 124Sn in comparison with 116Sn is correctly reproduced

  14. NEUTRON CROSS SECTION COVARIANCES FROM THERMAL ENERGY TO 20 MeV.

    ROCHMAN,D.; HERMAN, M.; OBLOZINSKY, P.; MUGHABGHAB, S.F.; PIGNI, M.; KAWANO, T.

    2007-04-27

    We describe new method for energy-energy covariance calculation from the thermal energy up to 20 MeV. It is based on three powerful basic components: (i) Atlas of Neutron Resonances in the resonance region; (ii) the nuclear reaction model code EMPIRE in the unresolved resonance and fast neutron regions, and (iii) the Bayesian code KALMAN for correlations and error propagation. Examples for cross section uncertainties and correlations on {sup 90}Zr and {sup 193}Ir illustrate this approach in the resonance and fast neutron regions.

  15. Microscopic optical potential calculations of finite nuclei with extended skyrme forces

    Microscopic optical potential calculations in the Hartree-Fock (HF) approximation with Extended Skyrme forces are investigated. The HF equation is derived from the variation principle and the potential formula of spherical nuclei is obtained by two different ways. Then the calculations for symmetrid nuclei 16O, 40Ca and asymmetric nucleus 90Zr with eight sets of Skyrme force parameters are presented. Our results show that the potential form and variating tendency with incident energy are reasonable and there apparently appears a 'wine-bottle-bottom' shape in the intermediate energy region. Furthermore, our calculations reflect shell effects clearly

  16. On the direct nucleon decay of high-spin subbarrier single-particle states in near-magic nuclei

    Chekomazov, G. A.; Urin, M. H.

    1996-01-01

    The description of the direct nucleon decay of high-spin subbarrier one-particle states in near-magic nuclei is attempted using a simple optical model and the simplest version of the coupled-channel approach. The branching ratios for the direct decay of the several single-neutron states in $^{209}Pb$ and $^{91}Zr$ to the ground state and to the low-lying collective states of $^{208}Pb$ and $^{90}Zr$, respectively, are evaluated. Results are compared with recent experimental data.

  17. The Gamow-Teller Resonance in Finite Nuclei in the Relativistic Random Phase Approximation

    Ma, Zhong-yu; Chen, Bao-qiu; Van Giai, Nguyen; Suzuki, Toshio

    2003-01-01

    Gamow-Teller(GT) resonances in finite nuclei are studied in a fully consistent relativistic random phase approximation (RPA) framework. A relativistic form of the Landau-Migdal contact interaction in the spin-isospin channel is adopted. This choice ensures that the GT excitation energy in nuclear matter is correctly reproduced in the non-relativistic limit. The GT response functions of doubly magic nuclei $^{48}$Ca, $^{90}$Zr and $^{208}$Pb are calculated using the parameter set NL3 and $g_0'...

  18. α clustering and superdeformation of 28Si

    Kimura M.

    2010-04-01

    Full Text Available We have studied positive-parity states of 28Si using antisymmetrized molecular dynamics and multiconfiguration mixing with constrained variation. Applying constraints to the cluster distance and the quadrupole deformation of the variational calculation, we have obtained basis wave functions that have various structures such as α-24Mg and 12C-16O cluster structures as well as deformed structures. Superposing those basis wave functions, we have obtained a oblate ground state band, a β vibration band, a normal-deformed prolate band, and a superdeformed band. It is found that the superdeformed bands contain large amounts of the α-24Mg cluster components. The results also suggest the presence of two excited bands with the developed α-24Mg cluster structure, where the inter-cluster motion and the 24Mg-cluster deformation play important roles.

  19. A Comparative Study of Proton-Emulsion and Heavy-Ion-Emulsion Interactions at 4.5 GeV/c per Nucleon

    Ghosh, D.; Sengupta, R.; Ghosh, A.; Mukhopadhyay, A.; Roy, J.

    This paper presents a comparative study of inelastic interactions of proton-Emulsion, 12C-Emulsion and 24Mg-Emulsion at 4.5 GeV/c per nucleon. The multiplicity distribution and their correlations have been studied. A strong correlation between ns and nh in case of 24Mg-Emulsion and 12C-Emulsion is observed which is not so in the case of proton-Emulsion interaction. It is also observed that ns increases with the increase of the projectile mass. The angular distribution of the target fragments in 24Mg-Emulsion and 12C-Emulsion interactions show massive forward collimations. Comparison is also made in the pseudorapidity distributions of 24Mg-Emulsion, 12C-Emulsion and proton-Emulsion interactions. The result shows many interesting features.Translated AbstractEine vergleichende Studie der Proton-Emulsion-Schwerionen-Emulsionwechselwirkung bei 4,5 GeV/c pro NucleonDie inelastischen Wechselwirkungen von Protonen, 12C- und 24Mg-Ionen mit Emulsionen werden verglichen. Dazu wird die Multiplizitätsverteilung und ihre Korrelationen untersucht. Es kann gezeigt werden, daß die Zahl der Schauerpartikel im Falle der 12C-, 24Mg-Emulsionwechselwirkungen fest zur Zahl der hochionisierenden Partikel korreliert ist und mit der Projektilmasse wächst. Die Schwerionenexperimente zeigen eine vorwärts collimierte, räumliche Verteilung der Targetfragmente. Die Pscudorapiditätsverteilung wird in allen Experimenten untersucht.

  20. Ca isotope cycling in a forested ecosystem

    Holmden, Chris; Bélanger, Nicolas

    2010-02-01

    Reports of large Ca isotope fractionations between trees and soils prompted this study of a Boreal forest ecosystem near La Ronge, Saskatchewan, to improve understanding of this phenomenon. The results on five tree species (black spruce, trembling aspen, white spruce, jack pine, balsam poplar) confirm that nutrient Ca uptake by plants favors the light isotopes, thus driving residual Ca in plant available soil pools towards enrichment in the heavy isotopes. Substantial within-tree fraction occurs in tissues formed along the transpiration stream, with low δ 44Ca values in fine roots (2 mm), intermediate values in stemwood, and high values in foliage. Separation factors between different plant tissues are similar between species, but the initial fractionation step in the tips of the fine roots is species specific, and/or sensitive to the local soil environment. Soil water δ 44Ca values appear to increase with depth to at least 35 cm below the top of the forest floor, which is close to the deepest level of fine roots. The heavy plant fractionated signature of Ca in the finely rooted upper soils filters downward where it is retained on ion exchange sites, leached into groundwater, and discharged into surface waters. The relationship between Ca uptake by tree fine roots and the pattern of δ 44Ca enrichment with soil depth was modeled for two Ca pools: the forest floor (litter) and the underlying (upper B) mineral soil. Six study plots were investigated along two hillside toposequences trending upwards from a first order stream. We used allometric equations describing the Ca distribution in boreal tree species to calculate weighted average δ 44Ca values for the stands in each plot and estimate Ca uptake rates. The δ 44Ca value of precipitation was measured, and soil weathering signatures deduced, by acid leaching of lower B mineral soils. Steady state equations were used to derive a set of model Ca fluxes and fractionation factors for each plot. The model reproduces

  1. Measurement of Compound Nucleus Space-Time Extent with Two-Neutron Correlation Functions

    Two-neutron relative-momentum correlation functions have been measured in the 130 MeV 18O+26Mg reaction. Differences in the longitudinal and transverse correlation functions, observed for the first time for neutrons, allow an independent determination of the spatial extent and the time scale for decay of the 44Ca compound nucleus. A comparison with theoretical calculations indicates a radius of 4.4±0.3 fm and an average neutron emission time scale of 1100±100 fm/c for 44Ca at 100 MeV excitation energy. Correlation functions selected by cuts on the total momentum of the neutron pair give a quantitative characterization of the cooling of a compound nucleus. copyright 1995 The American Physical Society

  2. Cluster formation in low-density condition

    We study cluster formation in low-density condition by using antisymmetrized molecular dynamics (AMD). We use the frictional cooling method constraining a root-mean-square radius to make low-density situation. We apply this method to 40Ca, 44Ca and 48Ca. We find that α cluster is the basic unit in any low density situation for 40Ca which is saturated by spin and isospin, and that the magic number n=8 plays an important role in cluster formation in low density situation in common with these three nuclei, and that the 14C cluster appears in case of 44Ca and 48Ca due to the neutron-rich property, and so on. (author)

  3. (α ,γ ) cross section measurements in the region of light p nuclei

    Quinn, S. J.; Spyrou, A.; Simon, A.; Battaglia, A.; Bowers, M.; Bucher, B.; Casarella, C.; Couder, M.; DeYoung, P. A.; Dombos, A. C.; Görres, J.; Kontos, A.; Li, Q.; Long, A.; Moran, M.; Paul, N.; Pereira, J.; Robertson, D.; Smith, K.; Smith, M. K.; Stech, E.; Talwar, R.; Tan, W. P.; Wiescher, M.

    2015-10-01

    The 90Zr(α ,γ )94Mo,92Zr(α ,γ )96Mo, and 74Ge(α ,γ )78Se reaction cross sections were measured for the first time in an effort to expand the existing experimental database for (α ,γ ) reactions relevant for the production of p nuclei in the universe. In particular, the 90Zr(α ,γ )94Mo reaction was identified by a sensitivity study for its potential impact on the γ -process mass flow in the region of light p nuclei. The measurements were performed for energies Eα=9.5 - 12.0 MeV at the University of Notre Dame using the SuN detector and the γ -summing technique. The results are compared to theoretical calculations from the talys and non-smoker nuclear reaction codes, and it is shown that the data greatly reduce the uncertainty in the cross section for the measured energies. The talys parameters that provide the best description of the experimental data are reported.

  4. p-process nucleosynthesis via proton-capture reactions in thermonuclear supernovae explosions

    Endres Anne

    2015-01-01

    Full Text Available Model calculations within the framework of the so-called γ process show an underproduction of the p nucleus with the highest isotopic abundace 92Mo. This discrepancy can be narrowed by taking into account the alternative production site of a type Ia supernova explosion. Here, the nucleus 92Mo can be produced by a sequence of proton-capture reactions. The amount of 92Mo nuclei produced via this reaction chain is most sensitive to the reactions 90Zr(p,γ and 91Nb(p,γ. Both rates have to be investigated experimentally to study the impact of this nucleosynthesis aspect on the long-standing 92Mo-problem. We have already measured the proton-capture reaction on 90Zr using high-resolution in-beam γ-ray spectroscopy. In this contribution, we will present our preliminary results of the total cross sections as well as the partial cross sections. Furthermore, we plan to measure the 91Nb(p,γ reaction soon. Due to the radioactive target material, the 91Nb nuclei have to be produced prior to the experiment. The current status of this production will be presented in this contribution.

  5. Investigation of reactions relevant for the γ process using in-beam γ-ray spectroscopy

    Netterdon, L.; Endres, J.; Mayer, J.; Sauerwein, A.; Scholz, P.; Zilges, A.

    2016-01-01

    The reaction 89Y(p, γ)90Zr was studied at five proton energies close to the Gamow window. This reaction is of astrophysical importance, since it is located in a mass region, where the p-nuclei abundances are not well reproduced by network calculations. For this purpose, the in-beam technique utilizing the high-efficiency high-purity germanium (HPGe) detector array HORUS at the Tandem ion accelerator at the University of Cologne was used. The excellent agreement of the measured total cross sections with previous data shows, that the setup in Cologne is well suited for such measurements. An additional interesting outcome of this measurement are partial cross sections of the de-excitation of the 90 Zr compund nucleus up to the 15th excited state, an observable only accessible in this kind of high-resolution inbeam experiments. The experimental setup and preliminary results of the total and partial cross sections obtained for the 89Y(p, γ) reaction are presented. Additionally, we show results of a first test measurement of the a-capture reaction on the p-nucleus 92Mo using the in-beam technique with HPGe detectors.

  6. Pygmy resonances and radiative nucleon captures for stellar nucleosynthesis

    Tsoneva, N.; Goriely, S.; Lenske, H.; Schwengner, R.

    2015-04-01

    The impact of low-energy multipole excitations and pygmy resonances on radiative neutron and proton-capture cross sections in nuclei close to the β -stability line is investigated. For this purpose, a microscopic theoretical approach based on self-consistent density functional theory and quasiparticle-random-phase-approximation formalism extended with multiphonon degrees of freedom is implemented in a statistical reaction model. The advantage of the method is the microscopic nuclear structure input for unified description of low-energy multiphonon excitations and pygmy and giant resonances. This is found to be important for the understanding of the fine structure and dynamics of the nuclear response function at low energies, which strongly influences nuclear reaction rates of astrophysical relevance. Calculations of the radiative capture cross sections of the reactions 85Kr (n ,γ )86Kr , 87Sr (n ,γ )88Sr , and 89Y (p ,γ )90Zr are discussed in comparison with experimental data. For the reactions 89Zr (n ,γ )90Zr and 91Mo (n ,γ )92Mo theoretical predictions of the reaction cross sections are made.

  7. Process for separating zirconium isotopes

    Chiang, P.T.; Lahoda, E.J.; Burgman, H.A.

    1986-04-22

    A method is described of separating a feed stream consisting essentially of an aqueous solution of a mixture of /sup 90/Zr and /sup 91 to 96/Zr salts selected from group consisting of thiocyanate, nitrate, sulfate, chloride, perchlorate, and mixtures thereof, into two aqueous product streams, each containing both a /sup 90/Zr isotopic portion and a /sup 91 to 96/Zr isotopic portion, but in different ratios. The method consists of: (A) contacting the feed stream with methylisobutyl ketone or an organic water-immiscible solvent containing an extractant medium selected from the group consisting of quaternary ammonium salts, organic phosphonates, organic phosphinates, organic phosphates, organic sulfonates, primary amines, tertiary amines, polyethers, betadiketones, and mixtures thereof, that preferentially extracts one of the isotopic portions, leaving an aqueous raffinate depleted in that isotopic portions and enriched in the other isotopic portion; (B) stripping the organic solvent of its zirconium with an aqueous acidic strip medium to produce a first aqueous product stream; (C) recycling the stripped organic solvent to step (A); (D) evaporating water from a portion of the aqueous raffinate to produce a concentrated aqueous raffinate and a second aqueous product stream; and (E) recycling the concentrated aqueous raffinate to the feed stream.

  8. Calcium isotopic composition of mantle peridotites

    Huang, F.; Kang, J.; Zhang, Z.

    2015-12-01

    Ca isotopes are useful to decipher mantle evolution and the genetic relationship between the Earth and chondrites. It has been observed that Ca isotopes can be fractionated at high temperature [1-2]. However, Ca isotopic composition of the mantle peridotites and fractionation mechanism are still poorly constrained. Here, we report Ca isotope composition of 12 co-existing pyroxene pairs in 10 lherzolites, 1 harzburgite, and 1 wehrlite xenoliths collected from Hainan Island (South Eastern China). Ca isotope data were measured on a Triton-TIMS using the double spike method at the Guangzhou Institute of Geochemistry, CAS. The long-term external error is 0.12‰ (2SD) based on repeated analyses of NIST SRM 915a and geostandards. δ44Ca of clinopyroxenes except that from the wehrlite ranges from 0.85‰ to 1.14‰, while opx yields a wide range from 0.98‰ up to 2.16‰. Co-existing pyroxene pairs show large ∆44Caopx-cpx (defined as δ44Caopx-δ44Cacpx) ranging from 0 to 1.23‰, reflecting equilibrium fractionation controlled by variable Ca contents in the opx. Notably, clinopyroxene of wehrlite shows extremely high δ44Ca (3.22‰). δ44Ca of the bulk lherzolites and harzburgites range from 0.86‰ to 1.14‰. This can be explained by extracting melts with slightly light Ca isotopic compositions. Finally, the high δ44Ca of the wehrlite (3.22‰) may reflect metasomatism by melt which has preferentially lost light Ca isotopes due to chemical diffusion during upwelling through the melt channel. [1] Amini et al (2009) GGR 33; [2] Huang et al (2010) EPSL 292.

  9. Ca cycling and isotopic fluxes in forested ecosystems in Hawaii

    Wiegand, B.A.; Chadwick, O.A.; Vitousek, P.M.; Wooden, J.L.

    2005-01-01

    Biogeochemical processes fractionate Ca isotopes in plants and soils along a 4 million year developmental sequence in the Hawaiian Islands. We observed that plants preferentially take up 40Ca relative to 44Ca, and that biological fractionation and changes in the relative contributions from volcanic and marine sources produce a significant increase in 44Ca in soil exchangeable pools. Our results imply moderate fluxes enriched in 44Ca from strongly nutrient-depleted old soils, in contrast with high 40Ca fluxes in young and little weathered environments. In addition, biological fractionation controls divergent geochemical pathways of Ca and Sr in the plant-soil system. While Ca depletes progressively with increasing soil age, Sr/Ca ratios increase systematically. Sr isotope ratios provide a valuable tracer for provenance studies of alkaline earth elements in forested ecosystems, but its usefulness is limited when deciphering biogeochemical processes involved in the terrestrial Ca cycle. Ca isotopes in combination with Sr/ Ca ratios reveal more complex processes involved in the biogeochemistry of Ca and Sr. Copyright 2005 by the American Geophysical Union.

  10. Antimuscarinic-induced convulsions in fasted animals after food intake: evaluation of the effects of levetiracetam, topiramate and different doses of atropine.

    Büget, Bahar; Türkmen, Aslı Zengin; Allahverdiyev, Oruc; Enginar, Nurhan

    2016-01-01

    This study evaluated the effects of different doses of atropine and new antiepileptics, levetiracetam and topiramate, on the development of convulsions triggered by food intake in antimuscarinic-treated fasted animals. Mice deprived of food for 24 h and treated i.p. with atropine at a dose of 2.4 or 24 mg/kg developed convulsions after being allowed to eat ad libitum. No convulsions were observed in fasted animals treated with 0.24 mg/kg atropine. There was no difference in the incidence of convulsions between the two atropine treatments, but latency to convulsions was longer in 24 mg/kg atropine treated animals. The lowest dose of atropine, 0.24 mg/kg, caused stage 1 and stage 2 activity, but did not provide the convulsive endpoint (stage 3, 4, 5 activity). Administration of levetiracetam (50 or 200 mg/kg) or topiramate (50 or 100 mg/kg) to another group of 24-h fasted mice was ineffective in reducing the incidence of convulsions developed in the animals after 2.4 mg/kg atropine treatment and food intake. However, the higher dose of levetiracetam prolonged the onset of convulsions. Present results demonstrated the efficacy of low and high doses of atropine on the development of convulsions in fasted animals and provided additional evidence for the ineffectiveness of antiepileptic treatment in these seizures. PMID:26453200

  11. Inelastic electron scattering at low momentum transfer

    Recent advances of high energy resolution (ΔE approx. 30 keV FWHM) inelastic electron scattering at low momentum transfer (q -1) using selected experimental data from the Darmstadt electron linear accelerator are discussed. Strong emphasis is given to a comparison of the data with theoretical nuclear model predictions. Of the low multipolarity electric transitions investigated, as examples only E1 transitions to unnatural parity states in 11B and E2 transitions of the very fragmented isoscalar quadrupole giant resonance in 208Pb are considered. In 11B the role of the Os hole in the configuration of the 1/2+, 3/2+ and 5/2+ states is quantitatively determined via an interference mechanism in the transition probability. By comparison of the high resolution data with RPA calculations the E2 EWSR in 208Pb is found to be much less exhausted than anticipated from previous medium energy resolution (e,e) and hadron scattering experiments. In the case of M1 transitions it is shown that the simplest idealized independent particle shell-model prediction breaks down badly. In 28Si, ground-state correlations influence largely the detected M1 strength and such ground-state correlations are also responsible for the occurence of a strong M1 transition to a state at Ex = 10.319 MeV in 40Ca. In 90Zr only about 10% of the theoretically expected M1 strength is seen in (e,e) and in 140Ce and 208Pb none (detection limit 1-2 μ2K). In the case of 208Pb high resolution spectra exist now up to an excitation energy of Ex = approx. 12MeV. The continuous decrease of the M1 strength with mass number is corroborated by the behaviour of strong but very fragmented M2 transitions which are detected in 28Si, 90Zr, 140Ce and 208Pb concentrated at an excitation energy E x approx. 44A-1/3MeV. In 90Zr, the distribution of spacings and widths of the many Jπ = 2 states are consistent with a Wigner and Porter-Thomas distribution, respectively. (orig.) 891 KBE/orig. 892 ARA

  12. Velocity and angular distributions of evaporation residues from /sup 32/S-induced reactions

    Hinnefeld, J.D.; Kolata, J.J.; Henderson, D.J.; Janssens, R.V.F.; Kovar, D.G.; Lesko, K.T.; Rosner, G.; Stephans, G.S.F.; van den Berg, A.M.; Wilkins, B.D.

    1987-09-01

    Velocity distributions of mass-resolved evaporation residues from reactions of /sup 32/S with /sup 12/C, /sup 24/Mg, /sup 27/Al, /sup 28/Si, and /sup 40/Ca have been measured at bombarding energies of 194, 239, and 278 MeV using time-of-flight techniques. In all cases, the observed shifts in the velocity centroids relative to the values expected for complete fusion are consistent with a previously reported parametrization of a threshold for onset of incomplete fusion. Angular distributions were measured and total cross sections extracted for the /sup 32/S+ /sup 24/Mg system at all three energies. A comparison with existing results for /sup 32/S+ /sup 24/Mg at lower energies, and with other systems leading to the /sup 56/Ni compound nucleus, suggests two different types of compound-nuclear limitations to complete fusion at higher energies.

  13. Evolution towards equilibration in orbiting interactions

    We have studied the evolution towards mass equilibration in 24Mg+16O orbiting interactions. 24Mg beams of energies between 75 and 115 MeV were used to bombard targets of 16O. Targetlike particles were detected at forward angles to determine the yields from orbiting interactions. The ratio of the orbiting yields of 12C and 16O exit channels rises continuously with energy from values below unity to above. The data are interpreted as demonstrating a strong entrance channel dependence at low energies, and an evolution towards mass equilibration with increasing energy

  14. Velocity distribution of fusion-like products for medium mass heavy-ion systems

    Reactions between 14N, 16O, 19F, 20Ne, 22Ne, 24Mg projectiles and 24Mg, 26Mg, 27Al, 28Si, 40Ca, 58Ni, 60Ni targets have been studied at 7-20 MeV/nucleon. The velocity distribution of nuclear fragments was measured in order to infer the velocity of the compound nucleus prior to decay. The dependences of the distribution on projectile energy and projectile type were obtained. Obtaining cross sections for reaction processes from the data is discussed

  15. Improvements on Semi-Classical Distorted-Wave model

    Sun Weili; Watanabe, Y.; Kuwata, R. [Kyushu Univ., Fukuoka (Japan); Kohno, M.; Ogata, K.; Kawai, M.

    1998-03-01

    A method of improving the Semi-Classical Distorted Wave (SCDW) model in terms of the Wigner transform of the one-body density matrix is presented. Finite size effect of atomic nuclei can be taken into account by using the single particle wave functions for harmonic oscillator or Wood-Saxon potential, instead of those based on the local Fermi-gas model which were incorporated into previous SCDW model. We carried out a preliminary SCDW calculation of 160 MeV (p,p`x) reaction on {sup 90}Zr with the Wigner transform of harmonic oscillator wave functions. It is shown that the present calculation of angular distributions increase remarkably at backward angles than the previous ones and the agreement with the experimental data is improved. (author)

  16. Evaluation of covariance for fission neutron spectra

    Kawano, Toshihiko; Nakashima, Hideki [Kyushu Univ., Fukuoka (Japan); Ohsawa, Takaaki; Shibata, Keiichi

    1999-02-01

    A covariance evaluation system for the evaluated nuclear data library JENDL-3.2 was established, and the covariance data for fission neutron spectra of {sup 233}U, {sup 235}U, {sup 238}U, {sup 239}Pu were evaluated. Two methods were employed to evaluate the covariance. One is based on the experimental data, and the other is based on a model calculation including some kinds of renormalizations. The latter technique was adopted for the covariance evaluation of the fission neutron spectra in JENDL-3.2. We performed an adjustment of the evaluated fission neutron spectrum of {sup 235}U using the spectrum averaged cross sections for the {sup 27}Al(n, p), {sup 46,47,48}Ti(n, p), {sup 54,56}Fe(n, p), {sup 58}Ni(n, p), {sup 90}Zr(n, 2n) reactions. The adjusted spectrum integrated over energy was found to be unity. (author)

  17. Are there nuclear structure effects on the isoscalar giant monopole resonance near A = 90?

    Gupta, Yogesh; Garg, Umesh; Howard, K.; Senyigit, M.; Itoh, M.; Ando, S.; Uchiyama, A.; Aoki, T.; Iwamoto, C.; Adachi, S.; Tamii, A.; Fujiwara, M.; Kadono, C.; Akimune, H.; Matsuda, Y.; Nakahara, T.; Kawabata, T.; Tsumura, M.; Furuno, T.; Harakeh, M.; Kalantar-Nayestanaki, N.

    2015-10-01

    The excitation energy of the isoscalar giant monopole resonance (ISGMR) exhibits, in general, a very smooth behavior (Ex ~A 1 / 3) over the periodic Table. In recent work the Texas A&M group has reported that ISGMR energies for 92Zr and 92Mo are appreciably higher than that for 90Zr, suggesting significant nuclear structure effects on ISGMR and, hence, on the nuclear compressibility. We have measured inelastic scattering of 385-MeV a particles on 90,92Zr, 92Mo at extremely forward angles, including 0°, using the ``Grand Raiden'' spectrometer at RCNP, Japan. Results of detailed multipole decomposition analyses to extract the ISGMR strength distributions in the three nuclei will be presented. Supported in part by the National Science Foundation (Grant No. PHY1419765).

  18. Low-energy enhancement of M1 strength

    Magnetic dipole strength functions have been deduced from averages of a large number of M1 transition strengths calculated within the shell model for the nuclides 90Zr, 94Mo, 95Mo, and 96Mo. An enhancement of M1 strength toward low transition energy has been found for all nuclides considered. Large M1 strengths appear for transitions between close-lying states with configurations including proton as well as neutron high-j orbits that re-couple their spins and add up their magnetic moments coherently. The M1 strength function deduced from the calculated M1 transition strengths is compatible with the low-energy enhancement found in (3He,3He') and (d,p) experiments. The present work presents an explanation of the experimental findings.

  19. Development of Enhanced, Permanently-Installed, Neutron Activation Diagnostic Hardware for NIF

    Edwards, E. R.; Jedlovec, D. R.; Carrera, J. A.; Yeamans, C. B.

    2016-05-01

    Neutron activation diagnostics are baseline neutron yield and flux measurement instruments at the National Ignition Facility. Up to 19 activation samples are distributed around the target chamber. Currently the samples must be removed to be counted, creating a 1-2 week data turn-around time and considerable labor costs. An improved system consisting of a commercially available LaBr3(Ce) scintillator and Power over Ethernet electronics is under development. A machined zirconium-702 cap over the detector is the activation medium to measure the 90Zr(n,2n)89Zr reaction. The detectors are located at the current neutron activation diagnostic sites and monitored remotely. Because they collect data in real time yield values are returned within a few hours after a NIF shot.

  20. Influence of multiple excitation of low lying states and giant resonances on heavy ion inelastic spectra

    The inelastic excitation probabilities of 40Ca, 90Zr and 208Pb impinged by 40Ca projectiles at bombarding energies between 10 and 100 MeV/nucleon are calculated in a model where the excitation amplitudes are evaluated along classical trajectories. The excited states are calculated in the random phase approximation and the nuclear and Coulomb excitations of both low lying states and giant resonances of the target and projectile are taken into account. A general feature of the calculated spectra for near grazing impact parameters and bombarding energies above 20 MeV/nucleon is the presence of broad regularly-spaced structures mainly due to the excitation of multiphonon states built with giant resonances. Cross section estimates for the inelastic excitations are given

  1. Proton-induced reactions on naturally composed zirconium

    Sauerwein, Anne; Erbacher, Philipp; Glorius, Jan; Goerres, Joachim; Sonnabend, Kerstin [Institut fuer Angewandte Physik, Goethe Universitaet Frankfurt am Main (Germany); Stech, Edward; Wiescher, Michael [Institute for Structure and Nuclear Astrophysics (ISNAP), University of Notre Dame, Indiana, USA (United States); Joint Institute of Nuclear Astrophysics (United States)

    2014-07-01

    Most reaction rates for the so-called p process, which produces the p nuclei, are adopted from Hauser-Feshbach-model (HFM) calculations. In order to improve the accuracy of theoretically predicted reaction rates, an improvement of its nuclear physics input is required. For this reason naturally composed zirconium was bombarded with protons at energies between 2 MeV and 10 MeV in order to determine cross sections of seven (p,γ) and (p,n) reactions using the activation technique. The irradiations and the γ-ray spectroscopy took place at the ISNAP of the University of Notre Dame, USA. These measurements allow systematic investigations of the proton-optical model potentials, an important input of the HFM, from the neutron closed-shell isotope {sup 90}Zr to the double subshell-closed isotope {sup 96}Zr. In this contribution we present our preliminary results.

  2. Proton-induced reactions on naturally composed zirconium

    Most reaction rates for the so-called p process, which produces the p nuclei, are adopted from Hauser-Feshbach-model (HFM) calculations. In order to improve the accuracy of theoretically predicted reaction rates, an improvement of its nuclear physics input is required. For this reason naturally composed zirconium was bombarded with protons at energies between 2 MeV and 10 MeV in order to determine cross sections of seven (p,γ) and (p,n) reactions using the activation technique. The irradiations and the γ-ray spectroscopy took place at the ISNAP of the University of Notre Dame, USA. These measurements allow systematic investigations of the proton-optical model potentials, an important input of the HFM, from the neutron closed-shell isotope 90Zr to the double subshell-closed isotope 96Zr. In this contribution we present our preliminary results.

  3. Systematics of intermediate energy proton nonelastic and neutron total cross section

    In order to examine the Letaw intermediate energy proton nonelastic cross section systematic formula, we chose the following 12 nuclei: 12C, 16O, 27Al, 40Ca, 56Fe, 63Cu, 90Zr, 107Ag, 118Su, 181Ta, 208Pb, and 238U, which have more experimental data. In order to examine the Pearlstein intermediate energy neutron total cross section systematic formula, we chose the following 10 nuclei: 12C, 16O, 27Al, 56Fe, 63Cu, 107Ag, 181Ta, 208Pb, 209Bi, and 238U, which have more experimental data. New systematic formulas for intermediate energy proton nonelastic and neutron total cross sections are obtained. 11 refs, 22 figs

  4. The gamma-ray spectrometer HORUS and its applications for nuclear astrophysics

    Netterdon, L; Endres, J; Fransen, C; Hennig, A; Mayer, J; Müller-Gatermann, C; Sauerwein, A; Scholz, P; Spieker, M; Zilges, A

    2014-01-01

    A dedicated setup for the in-beam measurement of absolute cross sections of astrophysically relevant charged-particle induced reactions is presented. These, usually very low, cross sections at energies of astrophysical interest are important to improve the modeling of the nucleosynthesis processes of heavy nuclei. Particular emphasis is put on the production of the $p$ nuclei during the astrophysical $\\gamma$ process. The recently developed setup utilizes the high-efficiency $\\gamma$-ray spectrometer HORUS, which is located at the 10 MV FN tandem ion accelerator of the Institute for Nuclear Physics in Cologne. The design of this setup will be presented and results of the recently measured $^{89}$Y(p,$\\gamma$)$^{90}$Zr reaction will be discussed. The excellent agreement with existing data shows, that the HORUS spectrometer is a powerful tool to determine total and partial cross sections using the in-beam method with high-purity germanium detectors.

  5. Exact calculation of nucleon nucleus spin orbit potential in Brueckner theory

    We have calculated the direct part of the spin orbit potential for the scattering of protons from 16O, 40Ca, 90Zr and 208Pb at 65 MeV to make a comparison of the spin orbit obtained by BR and our results obtained after removing the approximations which were assumed by BR. We have calculated the potential for different targets so as to study the mass number dependence of the calculated direct and imaginary parts of the spin orbit potential. We have employed Argonne v18 inter nucleon potential to solve Bethe-Goldstone integral equation to obtain t- matrices which were then folded numerically over the target densities. Effective mass correction has also been taken into account during the calculations. The nucleon densities used for the four targets were calculated using Relativistic mean field theory

  6. Towards a Microscopic Reaction Description Based on Energy Density Functionals

    Nobre, G P A; Escher, J E; Thompson, I J; Dupuis, M; Terasaki, J; Engel, J

    2011-01-01

    A microscopic calculation of reaction cross sections for nucleon-nucleus scattering has been performed by explicitly coupling the elastic channel to all particle-hole excitations in the target and one-nucleon pickup channels. The particle-hole states may be regarded as doorway states through which the flux flows to more complicated configurations, and subsequently to long-lived compound nucleus resonances. Target excitations for $^{40,48}$Ca, $^{58}$Ni, $^{90}$Zr and $^{144}$Sm were described in a random-phase framework using a Skyrme functional. Reaction cross sections obtained agree very well with experimental data and predictions of a state-of-the-art fitted optical potential. Couplings between inelastic states were found to be negligible, while the pickup channels contribute significantly. The effect of resonances from higher-order channels was assessed. Elastic angular distributions were also calculated within the same method, achieving good agreement with experimental data. For the first time observed a...

  7. Spin-isospin nuclear response using the existing microscopic Skyrme functionals

    Fracasso, Sara

    2007-01-01

    Our paper aims at providing an answer to the question whether one can reliably describe the properties of the most important spin-isospin nuclear excitations, by using the available non-relativistic Skyrme energy functionals. Our method, which has been introduced in a previous publication devoted to the Isobaric Analog states, is the self-consistent Quasiparticle Random Phase Approximation (QRPA). The inclusion of pairing is instrumental for describing a number of experimentally measured spherical systems which are characterized by open shells. We discuss the effect of isoscalar and isovector pairing correlations. Based on the results for the Gamow-Teller resonance in $^{90}$Zr, in $^{208}$Pb and in few Sn isotopes, we draw definite conclusions on the performance of different Skyrme parametrizations, and we suggest improvements for future fits. We also use the spin-dipole resonance as a benchmark of our statements.

  8. Low-energy enhancement of magnetic dipole radiation

    Schwengner, R; Larsen, A C

    2013-01-01

    Magnetic dipole strength functions have been deduced from averages of a large number of $M1$ transition strengths calculated within the shell model for the nuclides $^{90}$Zr, $^{94}$Mo, $^{95}$Mo, and $^{96}$Mo. An enhancement of $M1$ strength toward low transition energy has been found for all nuclides considered. Large $M1$ strengths appear for transitions between close-lying states with configurations including proton as well as neutron high-$j$ orbits that re-couple their spins and add up their magnetic moments coherently. The $M1$ strength function deduced from the calculated $M1$ transition strengths is compatible with the low-energy enhancement found in ($^3$He,$^3$He') and $(d,p)$ experiments. The present work presents for the first time an explanation of the experimental findings.

  9. 16O elastic scattering at Elab = 94 MeV/nucleon

    Elastic scattering of 94 MeV/nucleon 16O on 40Ca, 90Zr, and 208Pb was measured, completing similar measurements on 12C and 28Si. Optical model analysis of the whole set of data shows that the sensitive region where the nuclear potential is determined moves inwards as the mass of the target decreases. This determination is more precise for light systems which present a strong negative angle scattering contribution in the angular distribution. The data have also been analyzed in the framework of the folding model using density independent and density dependent nucleon-nucleon interaction. In both cases, the resulting potentials have to be renormalized to get a good description of the data. The data are consistent with a smooth decrease with energy of both the real and imaginary potentials. (orig.)

  10. New modes of nuclear excitations

    We present a theoretical approach based on density functional theory supplemented by a microscopic multi-phonon model which is applied for investigations of pygmy resonances and other excitations of different multipolarities in stable and exotic nuclei. The possible relation of low-energy modes to the properties of neutron or proton skins is systematically studied in isotonic and isotopic chains. Calculations have been performed for the following N=50 isotones: 88Sr, 90Zr, 92Mo and 86Kr up to 10 MeV. The fine structure of nuclear electric and magnetic response functions is analyzed and compared to experimental data. The agreement between data and calculations confirms the predictive power of our theoretical approach for the exploratory investigations of new modes of excitation

  11. The γ-ray spectrometer HORUS and its applications for nuclear astrophysics

    Netterdon, L., E-mail: lnetterdon@ikp.uni-koeln.de; Derya, V.; Endres, J.; Fransen, C.; Hennig, A.; Mayer, J.; Müller-Gatermann, C.; Sauerwein, A.; Scholz, P.; Spieker, M.; Zilges, A.

    2014-08-01

    A dedicated setup for the in-beam measurement of absolute cross-sections of astrophysically relevant charged-particle induced reactions is presented. These, usually very low, cross-sections at energies of astrophysical interest are important to improve the modeling of the nucleosynthesis processes of heavy nuclei. Particular emphasis is put on the production of the p nuclei during the astrophysical γ process. The recently developed setup utilizes the high-efficiency γ-ray spectrometer HORUS, which is located at the 10 MV FN tandem ion accelerator of the Institute for Nuclear Physics in Cologne. The design of this setup will be presented and results of the recently measured {sup 89}Y(p,γ){sup 90}Zr reaction will be discussed. The excellent agreement with existing data shows that the HORUS spectrometer is a powerful tool to determine total and partial cross-sections using the in-beam method with high-purity germanium detectors.

  12. Giant monopole transition densities within the local scale ATDHF approach

    Transition densities for 12C, 16O, 28Si, 32S, 40Ca, 48Ca, 56Ni, 90Zr, 208Pb even-even nuclei corresponding to nuclear glant monopole resonances obtained within a local-scale adiabatic time-dependent Hartree-Fook approach in terms of effective Skyrme-type forces SkM and S3. The approach, the particular form and all necessary coefficients of these transition densities are reported. They are of a simple analytical form and may be directly used for example in analyses of particle inelastic scattering on nuclei by distorted wave method and a such a way allowing a test of the theoretical interpretation of giant monopole resonances

  13. Localized 1hω particle-hole strength in nuclei

    A cross section enhancement, persisting to high momentum transfer, has been observed around 1hω in excitation energy in spectra from inelastic proton-, alpha- and electron scattering on 90Zr, 116Sn, 196Pt and 208Pb. Data are presented for (p,p') at 201 MeV, (α,α') at 120 MeV and analyzed together with existing data obtained with 133.8 MeV polarized ( vector p,p') on 116Sn and electron-scattering data on 116Sn and 196Pt. Two different interpretations of the observed enhancement are discussed: that of the incoherent sum of all 1hω cross section and alternatively the sum over the isoscalar normal modes of all multipolarities. ((orig.))

  14. Localized 1h{omega} particle-hole strength in nuclei

    Hofstee, M.A. [Rijksuniversiteit Groningen (Netherlands). Kernfysisch Versneller Inst.; Werf, S.Y. van der [Rijksuniversiteit Groningen (Netherlands). Kernfysisch Versneller Inst.; Berg, A.M. van den [Rijksuniversiteit Groningen (Netherlands). Kernfysisch Versneller Inst.; Blasi, N. [Dipartimento di Fisica dell` Universita and INFN, Sezione di Milano, I-20133 Milano (Italy); Bordewijk, J.A. [Rijksuniversiteit Groningen (Netherlands). Kernfysisch Versneller Inst.; Borghols, W.T.A. [National Institute for Nuclear Physics and High-Energy Physics, Section K, P.O. Box 41882, 1009 DB Amsterdam (Netherlands); De Leo, R. [Dipartimento di Fisica dell` Universita and INFN, Sezione di Bari, I-70126 Bari (Italy); Emery, G.T. [Department of Physics, Bowdoin College, Brunswick, ME 04011, USA, and Indiana University Cyclotron Facility, Bloomington, IN 47408 (United States); Fortier, S. [Institut de Physique Nucleaire, Orsay (France); Gales, S. [Institut de Physique Nucleaire, Orsay (France); Harakeh, M.N. [Rijksuniversiteit Groningen (Netherlands). Kernfysisch Versneller Inst.; Heijer, P. den [National Institute for Nuclear Physics and High-Energy Physics, Section K, P.O. Box 41882, 1009 DB Amsterdam (Netherlands); Jager, C.W. de [National Institute for Nuclear Physics and High-Energy Physics, Section K, P.O. Box 41882, 1009 DB Amsterdam (Netherlands); Langevin-Joliot, H. [Institut de Physique Nucleaire, Orsay (France); Micheletti, S. [Dipartimento di Fisica dell` Universita and INFN, Sezione di Milano, I-20133 Milano (Italy); Morlet, M. [Institut de Physique Nucleaire, Orsay (France); Pignanelli, M. [Dipartimento di Fisica dell` Universita and INFN, Sezione di Milano, I-20133 Milano (Italy); Schippers, J.M. [Rijksuniversiteit Groningen (Netherlands). Kernfysisch Versneller Inst.; Vries, R. de [National Institute for Nuclear Physics and High-Energy Physics, Section K, P.O. Box 41882, 1009 DB Amsterdam (Netherlands); Willis, A.

    1995-06-12

    A cross section enhancement, persisting to high momentum transfer, has been observed around 1h{omega} in excitation energy in spectra from inelastic proton-, alpha- and electron scattering on {sup 90}Zr, {sup 116}Sn, {sup 196}Pt and {sup 208}Pb. Data are presented for (p,p`) at 201 MeV, ({alpha},{alpha}`) at 120 MeV and analyzed together with existing data obtained with 133.8 MeV polarized ( vector p,p`) on {sup 116}Sn and electron-scattering data on {sup 116}Sn and {sup 196}Pt. Two different interpretations of the observed enhancement are discussed: that of the incoherent sum of all 1h{omega} cross section and alternatively the sum over the isoscalar normal modes of all multipolarities. ((orig.)).

  15. Collective aspects of 91Zr by (d,d/sup prime/) scattering at 17 MeV

    The 91Zr(d,d')91Zr( reaction has been investigated at 17 MeV incident energy. Up to 4.8 MeV excitation, 73 levels, some of them new, were identified. Angular distributions associated to approx.40 levels were attributed to pure L = 2, 3, or 5 excitations, concentrated in energy regions where the 90Zr core exhibits 2+, 3-, and 5- states. The partial deformation parameters β/sub L//sup prime/ obtained show agreement with those from low energy proton scattering for L = 2, but there is a systematic difference for L = 3 and L = 5, which is discussed. Attention is drawn to the high excitation probability of the first excited state of 91Zr, as measured by the β2approx. =0.18 value obtained, a factor of approx.2 above all other values for nuclei with A = 90 +- 2

  16. Collective aspects of /sup 91/Zr by (d,d/sup prime/) scattering at 17 MeV

    Horodynski-Matsushigue, L.B.; Borello-Lewin, T.; Dietzsch, O.

    1986-05-01

    The /sup 91/Zr(d,d')/sup 91/Zr( reaction has been investigated at 17 MeV incident energy. Up to 4.8 MeV excitation, 73 levels, some of them new, were identified. Angular distributions associated to approx.40 levels were attributed to pure L = 2, 3, or 5 excitations, concentrated in energy regions where the /sup 90/Zr core exhibits 2/sup +/, 3/sup -/, and 5/sup -/ states. The partial deformation parameters ..beta../sub L//sup prime/ obtained show agreement with those from low energy proton scattering for L = 2, but there is a systematic difference for L = 3 and L = 5, which is discussed. Attention is drawn to the high excitation probability of the first excited state of /sup 91/Zr, as measured by the ..beta../sub 2/approx. =0.18 value obtained, a factor of approx.2 above all other values for nuclei with A = 90 +- 2.

  17. Terminating Bands in {sup 98,99,100}Ru and Neutron 2d{sub 5/2} - 1g{sub 7/2} Energy Spacing

    J. Timar; J. Gizon; A. Gizon; B.M. Nyako; D. Sohler; L. Zolnai; A.J. Boston; D.T. Joss; E.S. Paul; A.T. Semple; N.J. O' Brien; C.M. Parry; I. Ragnarsson

    1999-12-31

    New high-spin bands have been established in {sup 98,99,100}Ru. Some are interpreted as terminating configurations using the Nilsson-Strutinsky cranking formalism. They are observed up to the predicted terminating states which are built from g{sub 9/2} protons and N = 3 proton holes combined with d{sub 5/2},g{sub 7/2} and h{sub 11/2} neutrons relative to a {sup 90}Zr core. The observed high-spin states assigned as terminating show systematic behavior and provide new information on the energy spacing between the 2d{sub 5/2} and 1g{sub 7/2} neutron subshells.

  18. Oscillation damping effect in elastic scattering cross sections of intermediate energy α-particles by atomic nuclei

    A simulating pattern of a scattering matrix based on the calculational results at eikonal approximation is used for theoretical analysis of differential cross sections of elastic scattering of α-particles with energies Eα>or approx. 100 MeV by atomic nuclei, in which the effect of attenuation of diffraction oscillations is observed. Calculated and measured cross sections of elastic scattering of α-particles by 12C, 40Ca and 90Zr nuclei in the energy region from 104.0-1725 MeV agree well between each other. The scattering matrix used in calculations corresponds to strong nuclear refraction and takes into acount transparence of target nuclei (from 2 to 16%) for waves with small moments

  19. Giant resonances based on unitarily transformed two-nucleon plus phenomenological three-nucleon interactions

    We investigate giant resonances of spherical nuclei on the basis of the Argonne V18 potential after unitary transformation within the similarity renormalization group or the unitary correlation operator method supplemented by a phenomenological three-body contact interaction. Such Hamiltonians can provide a good description of ground-state energies and radii within Hartree–Fock plus low-order many-body perturbation theory. The standard random phase approximation is applied here to calculate the isoscalar monopole, isovector dipole, and isoscalar quadrupole excitation modes of the 40Ca, 90Zr, and 208Pb nuclei. Thanks to the inclusion of the three-nucleon interaction and despite the minimal optimization effort, a reasonable agreement with experimental centroid energies of all three modes has been achieved. The role and scope of the Hartree–Fock reference state in RPA methods are discussed. (paper)

  20. Information content of nuclear masses: a covariance analysis

    In this contribution we show that the apparent irreconciliation can be eased if some highly asymmetric even-even spherical nuclei are additionally included in the fitting protocol of the optimization of the EDFs in microscopic mean-field models. The relativistic mean-field model (RMF) is chosen as the vehicle for the realization of our goal. For this purpose, two models (model-I and model-II) corresponding to different sets of fit-data are constructed. In model-I the binding energies and charge radii of some standard set of nuclei (16O, 40Ca, 48Ca, 56Ni, 68Ni, 90Zr, 100Sn, 116Sn, 132Sn, 144Sm and 208Pb) are taken as fit-data

  1. A new Skyrme interaction with improved spin-isospin properties

    Roca-Maza, X; Sagawa, H

    2012-01-01

    A correct determination of the spin-isospin properties of the nuclear effective interaction should lead, among other improvements, to an accurate description of the Gamow-Teller Resonances (GTR). These nuclear excitations impact on a variety of physical processes: from the response in charge-exchange reactions of nuclei naturally present in the Earth, to the description of the stellar nucleosynthesis, and of the pre-supernova explosion core-collapse evolution of massive stars in the Universe. A reliable description of the GTR provides also stringent tests for neutrinoless double-$\\beta$ decay calculations. We present a new Skyrme interaction as accurate as previous forces in the description of finite nuclei and of uniform matter properties around saturation density, and that accurately accounts for the GTR in ${}^{48}$Ca, ${}^{90}$Zr and ${}^{208}$Pb.

  2. Fuzzy barrier distributions

    Heavy-ion collisions often produce a fusion barrier distribution with structures displaying a fingerprint of couplings to highly collective excitations [1]. Basically the same distribution can be obtained from large-angle quasi-elastic scattering, though here the role of the many weak direct-reaction channels is unclear. For 20Ne + 90Zr we have observed the barrier structures expected for the highly deformed neon projectile, but for 20Ne + 92Zr we find completely smooth distribution (see Fig.1). We find that transfer channels in these systems are of similar strength but single particle excitations are significantly stronger in the latter case. They apparently reduce the 'resolving power' of the quasi-elastic channel, what leads to smeared out, or 'fuzzy' barrier distribution. This is the first case when such a phenomenon has been observed.(author)

  3. Progress of Covariance Evaluation at the China Nuclear Data Center

    Covariance evaluations at the China Nuclear Data Center focus on the cross sections of structural materials and actinides in the fast neutron energy range. In addition to the well-known Least-squares approach, a method based on the analysis of the sources of experimental uncertainties is especially introduced to generate a covariance matrix for a particular reaction for which multiple measurements are available. The scheme of the covariance evaluation flow is presented, and an example of n+90Zr is given to illuminate the whole procedure. It is proven that the accuracy of measurements can be properly incorporated into the covariance and the long-standing small uncertainty problem can be avoided

  4. Symmetry energy effects on isovector properties of neutron rich nuclei with a density functional approach

    Papazoglou, M C

    2014-01-01

    We employ a variational method to study the effect of the symmetry energy on the neutron skin thickness and the symmetry energy coefficients of various neutron rich nuclei. We concentrate our interest on $^{208}$Pb, $^{124}$Sn, $^{90}$Zr, and $^{48}$Ca, although the method can be applied in the totality of medium and heavy neutron rich nuclei. Our approach has the advantage that the isospin asymmetry function $\\alpha(r)$, which is the key quantity to calculate isovector properties of various nuclei, is directly related with the symmetry energy as a consequence of the variational principle. Moreover, the Coulomb interaction is included in a self-consistent way and its effects can be separated easily from the nucleon-nucleon interaction. We confirm, both qualitatively and quantitatively, the strong dependence of the symmetry energy on the various isovector properties for the relevant nuclei, using possible constraints between the slope and the value of the symmetry energy at the saturation density.

  5. Neutron capture on (94)Zr: Resonance parameters and Maxwellian-averaged cross sections

    Tagliente, G; Fujii, K; Abbondanno, U; Aerts, G; Alvarez, H; Alvarez-Velarde, F; Andriamonje, S; Andrzejewski, J; Audouin, L; Badurek, G; Baumann, P; Becvar, F; Belloni, F; Berthoumieux, E; Bisterzo, S; Calvino, F; Calviani, M; Cano-Ott, D; Capote, R; Carrapico, C; Cennini, P; Chepel, V; Chiaveri, E; Colonna, N; Cortes, G; Couture, A; Cox, J; Dahlfors, M; David, S; Dillmann, I; Domingo-Pardo, C; Dridi, W; Duran, I; Eleftheriadis, C; Embid-Segura, M; Ferrari, A; Ferreira-Marques, R; Furman, W; Gallino, R; Goncalves, I; Gonzalez-Romero, E; Gramegna, F; Guerrero, C; Gunsing, F; Haas, B; Haight, R; Heil, M; Herrera-Martinez, A; Jericha, E; Kappeler, F; Kadi, Y; Karadimos, D; Karamanis, D; Kerveno, M; Kossionides, E; Krticka, M; Lamboudis, C; Leeb, H; Lindote, A; Lopes, I; Lozano, M; Lukic, S; Marganiec, J; Marrone, S; Martinez, T; Massimi, C; Mastinu, P; Mengoni, A; Moreau, C; Mosconi, M; Neves, F; Oberhummer, H; O'Brien, S; Pancin, J; Papachristodoulou, C; Papadopoulos, C; Paradela, C; Patronis, N; Pavlik, A; Pavlopoulos, P; Perrot, L; Pigni, M.T; Plag, R; Plompen, A; Plukis, A; Poch, A; Praena, J; Pretel, C; Quesada, J; Rauscher, T; Reifarth, R; Rosetti, M; Rubbia, C; Rudolf, G; Rullhusen, P; Salgado, J; Santos, C; Sarchiapone, L; Savvidis, I; Stephan, C; Tain, J.L; Tassan-Got, L; Tavora, L; Terlizzi, R; Vannini, G; Vaz, P; Ventura, A; Villamarin, D; Vincente, M.C; Vlachoudis, V; Vlastou, R; Voss, F; Walter, S; Wiescher, M; Wisshak, K

    2011-01-01

    The neutron capture cross sections of the Zr isotopes play an important role in nucleosynthesis studies. The s-process reaction flow between the Fe seed and the heavier isotopes passes through the neutron magic nucleus (90)Zr and through (91,92,93,94)Zr, but only part of the flow extends to (96)Zr because of the branching point at (95)Zr. Apart from their effect on the s-process flow, the comparably small isotopic (n, gamma) cross sections make Zr also an interesting structural material for nuclear reactors. The (94)Zr (n, gamma) cross section has been measured with high resolution at the spallation neutron source n_TOF at CERN and resonance parameters are reported up to 60 keV neutron energy.

  6. Activation cross sections related to nuclear heating of high Tc superconductors

    Activation cross-sections have been measured for some isotopes of the elements in Tl2Ca1Ba2Cu2O8 high Tc superconducting oxide. In addition, cross-sections for producing long-lived isotopes in Cu and Ag were also determined. Results for the following reactions were given at En = 14.5 MeV: 63Cu(n,α)60gCo, 90Zr(n,2n)89Zr, 107Ag(n,2n)106mAg, 109Ag(n,2n)108mAg, 134Ba(n,2n)133gBa, 134Ba(n,p)134gCs, 136Ba(n,p)136Cs, 137Ba(n,p)137Cs and 203Tl(n,2n)202Tl. Results are compared to the corresponding data published in the literature and given by systematics. (author). 9 refs, 1 fig., 2 tabs

  7. Systematics of the excitation of M1 resonances in medium heavy nuclei by 200 MeV proton inelastic scattering

    In a series of seventeen nuclei ranging from 51V to 140Ca, broad resonance structures are observed at energies between 8 and 10 MeV, nearly mass independent. These resonances have very forward peaked angular distributions which imply that they are populated by an angular momentum transfer of zero. This together with the observed excitation energies suggests an M1 character for these resonances. In 51V, 58Ni, 60Ni, 62Ni, a sharp peak located at an excitation energy above the threshold for neutron emission is interpreted as a part of the T0+1 component of the M1 resonances. Cross-sections are given for all the M1 resonances. For 58Ni, 90Zr, 92Mo, 120Sn and 140Ca, an ''attenuation'' factor for the cross-sections is extracted in a OWIA calculation assuming simple shell model structures for these resonances

  8. Nuclear structure effects in high-energy bremsstrahlung from spin-0 and spin-1/2 nuclei

    Jakubassa-Amundsen, Doris [University of Munich (Germany)

    2014-07-01

    Bremsstrahlung from relativistic spin-polarized electrons colliding with inert nuclei is calculated by taking into account the nuclear form factors and the kinematical recoil. For the spin-1/2 nuclei additional contributions from the anomalous magnetic moment and the dynamical recoil are considered. Electron bremsstrahlung is described with the help of semirelativistic wavefunctions while nuclear bremsstrahlung, when present, is treated within the Born approximation. The triply differential bremsstrahlung cross section is integrated over the electron scattering angle to study the polarization correlations between the beam electron and the emitted photon. Results are shown for 20-120 MeV electrons colliding with protons, 19F, 64Zn and 89Y. It is also attempted to explain the background in electron spectra from nuclear excitation in terms of bremsstrahlung. As an example the 180 degree spectrum from exciting the giant M2 resonance in 90Zr by 42.7 MeV electrons is analyzed.

  9. A consistent analysis of (p,p`) and (n,n`) reactions using the Feshbach-Kerman-Koonin model

    Yoshioka, S.; Watanabe, Y.; Harada, M. [Kyushu Univ., Fukuoka (Japan)] [and others

    1997-03-01

    Double-differential proton emission cross sections were measured for proton-induced reactions on several medium-heavy nuclei ({sup 54,56}Fe, {sup 60}Ni, {sup 90}Zr, and {sup 93}Nb) at two incident energies of 14.1 and 26 MeV. The (p,p`) data for {sup 56}Fe and {sup 93}Nb were compared with available data of (n,n`) scattering for the same target nuclei and incident energies, and both data were analyzed using the Feshbach-Kerman-Koonin model to extract the strength V{sub 0} of the effective N-N interaction which is the only free parameter used in multistep direct calculations. (author)

  10. What happens actually in multinucleon transfer reactions?

    In the 90Zr+208Pb reaction at 560 MeV identical Gaussian isotopic distributions having a width of 2.5 u are observed for products of Z comprised between 40 and 32: Are they really due to a multineutron pick-up process accompanying any proton stripping, as believed today? In fact they are distributions of the neutron number N of the product around its most probable value: This uncertainty in N results from the lifetime of only 0.17 yoctosecond of a new state of nuclear matter, which has been also found in the fission reaction. Interestingly, the new state is characterized by the disappearance of any proton charge and might be triggered, in fission, by a combined shifting of the proton phase against the neutron phase of ordinary matter: It may be asked whether this state is triggered, in transfer reactions, by the crossing of the Coulomb barrier, at which any proton charge should logically disappear.