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Sample records for 141pr 197au nattl

  1. Symmetry energy from elliptic flow in 197Au + 197Au

    NASA Astrophysics Data System (ADS)

    Russotto, P.; Wu, P. Z.; Zoric, M.; Chartier, M.; Leifels, Y.; Lemmon, R. C.; Li, Q.; Łukasik, J.; Pagano, A.; Pawłowski, P.; Trautmann, W.

    2011-03-01

    The elliptic-flow ratio of neutrons with respect to protons or light complex particles in reactions of neutron-rich systems at relativistic energies is proposed as an observable sensitive to the strength of the symmetry term in the equation of state at supra-normal densities. The results obtained from the existing FOPI/LAND data for 197Au + 197Au collisions at 400 MeV/nucleon in comparison with the UrQMD model favor a moderately soft symmetry term with a density dependence of the potential term proportional to (ρ /ρ0) γ with γ = 0.9 ± 0.4.

  2. Onset of nuclear vaporization in [sup 197]Au+[sup 197]Au collisions

    SciTech Connect

    Tsang, M.B.; Hsi, W.C.; Lynch, W.G.; Bowman, D.R.; Gelbke, C.K.; Lisa, M.A.; Peaslee, G.F. ); Kunde, G.J.; Begemann-Blaich, M.L.; Hofmann, T.; Hubele, J.; Kempter, J.; Kreutz, P.; Kunze, W.D.; Lindenstruth, V.; Lynen, U.; Mang, M.; Mueller, W.F.J.; Neumann, M.; Ocker, B.; Ogilvie, C.A.; Pochodzalla, J.; Rosenberger, F.; Sann, H.; Schuettauf, A.; Serfling, V.; Stroth, J.; Trautmann, W.; Tucholski, A.; Woerner, A.; Zude, E.; Zwieglinski, B. ); Aiello, S.; Imme, G.; Pappalardo, V.; Raciti, G. ); Charity, R.J.; Sobotka, L.G. ); Iori, I.; Moroni, A.; Scardoni, R.; Ferr

    1993-09-06

    Multifragmentation has been measured for [sup 197]Au+[sup 197]Au collisions at [ital E]/[ital A]=100, 250, and 400 MeV. The mean fragment multiplicity increases monotonically with the charged particle multiplicity at [ital E]/[ital A]=100 MeV, but decreases for central collisions with incident energy, consistent with the onset of nuclear vaporization. Molecular dynamics calculations follow some trends but underpredict the observed fragment multiplicities. Including the statistical decay of excited residues improves the agreement for peripheral collisions but worsens it for central collisions.

  3. Fast Ternary and Quaternary Breakup of the {sup 197}Au+{sup 197}Au System in Collisions at 15 MeV/nucleon

    SciTech Connect

    Skwira-Chalot, I.; Siwek-Wilczynska, K.; Wilczynski, J.; Swiderski, L.; Auditore, L.; Trifiro, A.; Trimarchi, M.; Baran, V.; Brzychczyk, J.

    2008-12-31

    A new reaction mechanism of violent reseparation of a heavy nucleus-nucleus system, {sup 197}Au+{sup 197}Au, into three or four massive fragments in collisions at 15 MeV/nucleon has been observed. After reseparation, the fragments are almost exactly aligned, thus showing a very short time scale of the reseparation process, of about 70-80 fm/c.

  4. Near-Barrier Neutron Transfer in Reactions 3,6He+197Au

    NASA Astrophysics Data System (ADS)

    Samarin, V. V.; Naumenko, M. A.; Penionzhkevich, Yu. E.; Skobelev, N. K.; Kroha, V.; Mrazek, J.

    2015-06-01

    Experimental excitation functions for near-barrier neutron transfer in 3,6He+197Au reactions have been measured and analyzed. Time-dependent Schrödinger equation and coupled channel equations for external neutrons of 3,6He and 197Au nuclei have been solved numerically taking into account spin-orbit interaction and Pauli exclusion principle.

  5. Rapidity and centrality dependence of proton and anti-proton production from 197Au+197Au collisions at {radical}(s{sub NN}) = 130 GeV

    SciTech Connect

    Adams, J.; Adler, C.; Aggarwal, M.M.; Ahammed, Z.; Amonett, J.; Anderson, B.D.; Anderson, M.; Arkhipkin, D.; Averichev, G.S.; Badyal, S.K.; Balewski, J.; Barannikova, O.; Barnby, L.S.; Baudot, J.; Bekele, S.; Belaga, V.V.; Bellwied, R.; Berger, J.; Bezverkhny, B.I.; Bhardwaj, S.; Bhaskar, P.; Bhati, A.K.; Bichsel, H.; Billmeier, A.; Bland, L.C.; Blyth, C.O.; Bonner, B.E.; Botje, M.; Boucham, A.; Brandin, A.; Bravar, A.; Cadman, R.V.; Cai, X.Z.; Caines, H.; Calderon de la Barca Sanchez, M.; Cardenas, A.; Carroll, J.; Castillo, J.; Castro, M.; Cebra, D.; Chaloupka, P.; Chattopadhyay, S.; Chen, H.F.; Chen, Y.; Chernenko, S.P.; Cherney, M.; Chikanian, A.; Choi, B.; Christie, W.; Coffin, J.P.; Cormier, T.M.; Corral, M.M.; Cramer, J.G.; Crawford, H.J.; Das, D.; Das, S.; Derevschikov, A.A.; Didenko, L.; Dietel, T.; Dong, X.; Draper, J.E.; Du, F.; Dubey, A.K.; Dunin, V.B.; Dunlop, J.C.; Dutta Mazumdar, M.R.; Eckardt, V.; Efimov, L.G.; Emelianov, V.; Engelage, J.; Eppley, G.; Erazmus, B.; Fachini, P.; Faine, V.; Faivre, J.; Fatemi, R.; Filimonov, K.; Filip, P.; Finch, E.; Fisyak, Y.; Flierl, D.; Foley, K.J.; Fu, J.; Gagliardi, C.A.; Ganti, M.S.; Gutierrez, T.D.; Gagunashvili, N.; Gans, J.; Gaudichet, L.; Germain, M.; Geurts, F.; Ghazikhanian, V.; Ghosh, P.; Gonzalez, J.E.; Grachov, O.; Grigoriev, V.; Grosnick, D.; Guedon, M.; Guertin, S.M.; Gupta, A.; Gushin, E.; Hallman, T.J.; Hardtke, D.; Harris, J.W.; Heinz, M.; Henry, T.W.; Heppelmann, S.; Herston, T.; Hippolyte, B.; Hirsch, A.; Hjort, E.; Hoffmann, G.W.; Horsley, M.; Huang, H.Z.; Huang, S.L.; Humanic, T.J.; Igo, G.; Ishihara, A.; Jacobs, P.; Jacobs, W.W.; Janik, M.; Johnson, I.; Jones, P.G.; Judd, E.G.; Kabana, S.; Kaneta, M.; Kaplan, M.; Keane, D.; Kiryluk, J.; Kisiel, A.; Klay, J.; Klein, S.R.; Klyachko, A.; Koetke, D.D.; Kollegger, T.; Konstantinov, A.S.; Kopytine, M.; Kotchenda, L.; Kovalenko, A.D.; Kramer, M.; Kravtsov, P.; Krueger, K.; Kuhn, C.; Kulikov, A.I.; Kumar, A.; et al.

    2003-06-20

    We report on the rapidity and centrality dependence of proton and anti-proton transverse mass distributions from {sup 197}Au + {sup 197}Au collisions at {radical}s{sub NN} = 130 GeV as measured by the STAR experiment at RHIC. Our results are from the rapidity and transverse momentum range of |y| < 0.5 and 0.35 < p{sub t} < 1.00 GeV/c. For both protons and anti-protons, transverse mass distributions become more convex from peripheral to central collisions demonstrating characteristics of collective expansion. The measured rapidity distributions and the mean transverse momenta versus rapidity are flat within |y| < 0.5. Comparisons of our data with results from model calculations indicate that in order to obtain a consistent picture of the proton(anti-proton) yields and transverse mass distributions the possibility of pre-hadronic collective expansion may have to be taken into account.

  6. Yields of photoneutron reactions on {sup 197}Au nuclei in the giant-dipole-resonance region

    SciTech Connect

    Belyshev, S. S.; Ermakov, A. N.; Ishkhanov, B. S.; Kuznetsov, A. A.; Kurilik, A. S.; Stopani, K. A.; Troschiev, S. Yu.

    2011-11-15

    Yields of photonuclear reactions on 197Au nuclei were measured in a beam of bremsstrahlung photons, the endpoint energy of the bremsstrahlung spectrum being 29.1 MeV. These measurements were performed by means of the gamma-activation procedure. The results obtained in this way were compared with the results of earlier experiments and theoretical calculations.

  7. Observation of fast collinear partitioning of the {sup 197}Au + {sup 197}Au system into three and four fragments of comparable size

    SciTech Connect

    Wilczynski, J.; Swiderski, L.; Pagano, A.; Cardella, G.; De Filippo, E.; Guidara, E. La; Papa, M.; Pirrone, S.; Amorini, F.; Anzalone, A.; Cavallaro, S.; Colonna, M.; Toro, M. Di; Maiolino, C.; Porto, F.; Rizzo, F.; Russotto, P.; Auditore, L.

    2010-02-15

    Collisions of a very heavy nonfusing nuclear system {sup 197}Au+{sup 197}Au were studied at an energy of 15 MeV/nucleon. An interesting process of violent reseparation of this heavy system into three or four fragments of comparable size was observed. In the case of ternary partitioning, either the projectile-like fragment (PLF) or target-like fragment (TLF) breaks up almost collinearly with the PLF-TLF separation axis. In the case of quaternary reactions, both PLF and TLF were observed breaking up along this direction. By comparison with a dynamical model of deep inelastic collisions it was concluded that the ternary and quaternary reactions occur in semiperipheral collisions, in a range of angular momenta corresponding to about 0.5-0.7 of the maximum L value for grazing collisions. The time elapsing from the scission of the binary PLF + TLF system to the secondary scission of PLF or TLF was estimated to be of about 70-80 fm/c for the ternary reactions and 80-100 fm/c for the quaternary reactions.

  8. Photon and Neutral Pi 0 production in (197)Au + (197)Au collisions at sqrt S(NN) = 130 GeV

    SciTech Connect

    Johnson, Ian J.

    2002-09-16

    Inclusive transverse momentum spectra of photons and {pi}{sup 0}s at mid-rapidity are studied as a function of collision centrality for {sup 197}Au+ {sup 197}Au collisions at {radical}s{sub NN} = 130 GeV. Photon pair conversions have been reconstructed from charged tracks measured by the main Time Project Chamber of the STAR experiment at the RHIC heavy ion facility. The transverse momentum resolution of photons with this method is estimated to be {Delta}p{sub t}/p{sub t} = 2% at 0.125 GeV/c and 5% at 2.5 GeV/c. Photon spectra were measured up to a transverse momentum of 2.4 GeV/c between {+-} 0.5 units of rapidity. The dominant photon production mechanism, the {pi}{sup 0} {yields} {gamma}{gamma} decay, was measured between 0.25-2.5 GeV/c and {+-} 1 units of rapidity. Spectra are reported for the top 11%, 11-34% and 34-85% centrality classes. It was observed that in mid-central and central collisions the relative contribution of the {pi}{sup 0} {yields} {gamma}{gamma} decay to the inclusive photon spectrum decreases above a transverse momentum of 1.65 GeV/c. In central collisions the magnitude of the decrease from p{sub t} = 1.65 GeV/c to 2.4 GeV/c is 20%. It is unlikely that contributions from other {pi}{sup 0} decay channels and other particle decays fully explain this decrease. The centrality dependence on the shapes of the {pi}{sup 0} spectra was analyzed with Boltmann and Bose-Einstein functions. In the transverse momentum windows of the spectra, the extracted temperatures are near 0.295 GeV. These temperatures are substantially higher than those extracted from {pi}{sup {+-}} spectra in a lower range of transverse momentum. This is an indication that the shapes of the pion spectra deviate from purely exponential shapes.

  9. Near-barrier neutron transfer in reactions 3,6He + 45Sc and 3,6He + 197Au

    NASA Astrophysics Data System (ADS)

    Samarin, V. V.; Naumenko, M. A.; Penionzhkevich, Yu E.; Skobelev, N. K.; Kroha, V.; Mrazek, J.

    2016-06-01

    Experimental cross sections for formation of 196,198Au isotopes in reactions 3,6He + 197Au and cross sections for formation of 44,46Sc isotopes in reactions 3,6He + 45Sc have been analyzed. To calculate neutron transfer probabilities and cross sections the time- dependent Schrödinger equation for external neutrons of 3He, 6He, 45Sc and 197Au nuclei has been solved numerically. It is shown that the contribution of fusion and subsequent evaporation is significant in the case of reactions 3,6He + 45Sc, whereas in the case of reactions 3,6He + 197Au, it is negligible. Fusion-evaporation was taken into account using NRV evaporation code. Results of calculations demonstrate overall satisfactory agreement with experimental data.

  10. {sup 197}Au(n,gamma) cross section in the resonance region

    SciTech Connect

    Massimi, C.; Vannini, G.; Domingo-Pardo, C.; Audouin, L.; David, S.; Ferrant, L.; Stephan, C.; Tassan-Got, L.; Abbondanno, U.; Belloni, F.; Fujii, K.; Milazzo, P. M.; Moreau, C.

    2010-04-15

    The (n,gamma) cross section of {sup 197}Au has been measured at n{sub T}OF in the resolved resonance region, up to 5 keV, with the aim of improving the accuracy in an energy range where it is not yet considered standard. The measurements were performed with two different experimental setup and detection techniques, the total energy method based on C{sub 6}D{sub 6} detectors, and the total absorption calorimetry based on a 4pi BaF{sub 2} array. By comparing the data collected with the two techniques, two accurate sets of neutron-capture yields have been obtained, which could be the basis for a new evaluation leading to an extended cross-section standard. Overall good agreement is found between the n{sub T}OF results and evaluated cross sections, with some significant exceptions for small resonances. A few resonances not included in the existing databases have also been observed.

  11. Isomeric cross section of the {sup 197}Au(n,2n) reaction

    SciTech Connect

    Tsinganis, A.; Diakaki, M.; Kokkoris, M.; Mara, E.; Papadopoulos, C. T.; Vlastou, R.; Lagoyannis, A.

    2011-02-15

    In the present work, the {sup 197}Au(n,2n) reaction cross section is experimentally determined relative to the {sup 27}Al(n,{alpha}){sup 24}Na reaction at incident neutron energies of 9.0-10.5 MeV by means of the activation technique. The quasimonoenergetic fast neutron beam was produced via the {sup 2}H(d,n){sup 3}He reaction at the 5.5-MV Tandem Van de Graaff accelerator at the National Centre of Scientific Research (NCSR) ''Demokritos'' and was studied to determine the contribution of background 'parasitic' neutrons using the multiple foil activation technique and the SULSA unfolding code. The cross sections for the population of the second isomeric state (12{sup -}) of {sup 196}Au and the sum of the ground (2{sup -}) and first isomeric state (5{sup -}) population cross sections were independently determined. Auxiliary Monte Carlo simulations were performed with the MCNP code. Theoretical calculations of the above cross sections in the 8-25 MeV region were carried out with the use of the STAPRE-F, EMPIRE, and TALYS codes, which were also compared in their implementation of the generalized superfluid model. The theoretical results are compared with previous work in the same mass region, and the strong dependence on the level scheme of the nuclei involved was revealed.

  12. 197Au(n,gamma) Cross Section in the Unresolved Resonance Region

    SciTech Connect

    Lederer, C.; Koehler, Paul Edward

    2011-03-01

    The cross section of the reaction {sup 197}Au(n,{gamma}) was measured with the time-of-flight technique at the n{_}TOF (neutron time-of-flight) facility in the unresolved resonance region between 5 and 400 keV using a pair of C{sub 6}D{sub 6} (where D denotes {sup 2}H) liquid scintillators for the detection of prompt capture {gamma} rays. The results with a total uncertainty of 3.9%-6.7% for a resolution of 20 bins per energy decade show fair agreement with the Evaluated Nuclear Data File Version B-VII.0 (ENDF/B-VII.0), which contains the standard evaluation. The Maxwellian-averaged cross section (MACS) at 30 keV is in excellent agreement with the one according to the ENDF/B-VII.0 evaluation and 4.7% higher than the MACS measured independently by activation technique. Structures in the cross section, which had also been reported earlier, have been interpreted as being due to clusters of resonances.

  13. Yield Of Radioactive Products Of Transfer Reactions Induced By {sup 6}He Ions On {sup 197}Au Target

    SciTech Connect

    Chuvilskaya, T. V.; Shirokova, A. A.; Demekhina, N. A.; Kulko, A. A.; Penionzhkevich, Yu. E.; Skobelev, N. K.

    2011-10-28

    The excitation functions and isomeric cross section ratios of Tl isotopes obtained at irradiation of {sup 197}Au by a {sup 6}He-ions beams with energies from 15 to 60 MeV are analyzed. The EMPIRE-2.18 code which takes into account the branching ratios of gamma-transitions of discrete gamma-cascade in a residual nucleus in the calculations of the cross sections of the isomeric and ground nuclear states production is used.

  14. Complete and Incomplete Fusion Competition in 11B-INDUCED Fission Reactions on 197Au at the Intermediate Energy

    NASA Astrophysics Data System (ADS)

    Demekhina, N. A.; Karapetyan, G. S.; Balabekyan, A. R.

    2015-06-01

    Above Coulomb barrier cross sections of fission fragment production were measured in reactions of 11B with 197Au target. Induced-activity method was used for measurement the fission decay channel of the composite nuclei. Systematic of the fission fragment charge and mass distributions was used for fission cross section calculation. Fission fraction of the composite nuclei decay was compared with PACE-4 mode calculations. Estimated suppression for fission fraction followed the complete fusion have been obtained 35%.

  15. Excitation functions for {sup 208-211}Fr produced in the {sup 18}O+{sup 197}Au fusion reaction

    SciTech Connect

    Corradi, L.; Behera, B.R.; Fioretto, E.; Gadea, A.; Latina, A.; Stefanini, A.M.; Szilner, S.; Trotta, M.; Wu, Y.; Beghini, S.; Montagnoli, G.; Scarlassara, F.; Sagaidak, R.N.; Atutov, S.N.; Mai, B.; Stancari, G.; Tomassetti, L.; Mariotti, E.; Khanbekyan, A.; Veronesi, S.

    2005-01-01

    Excitation functions for {sup 208-211}Fr isotopes produced in the {sup 18}O+{sup 197}Au fusion-evaporation reaction have been measured at E{sub lab}=75-130 MeV via characteristic {alpha} decays by means of an electrostatic deflector and a semiconductor detector. Data have been compared with calculations giving barrier-passing (capture) cross sections and probabilities of the compound nucleus decay into different channels according to the standard statistical model.

  16. Neutron capture cross section measurements for 197Au from 3.5 to 84 keV at GELINA

    NASA Astrophysics Data System (ADS)

    Massimi, C.; Becker, B.; Dupont, E.; Kopecky, S.; Lampoudis, C.; Massarczyk, R.; Moxon, M.; Pronyaev, V.; Schillebeeckx, P.; Sirakov, I.; Wynants, R.

    2014-08-01

    Cross section measurements have been performed at the time-of-flight facility GELINA to determine the average capture cross section for 197Au in the energy region between 3.5 keV and 84 keV. Prompt γ-rays, originating from neutron-induced capture events, were detected by two C6 D6 liquid scintillators. The sample was placed at about 13m distance from the neutron source. The total energy detection principle in combination with the pulse height weighting technique was applied. The energy dependence of the neutron flux was measured with a double Frisch-gridded ionization chamber based on the 10B(n,α) reaction. The data have been normalized to the well-isolated and saturated 197Au resonance at 4.9 eV. Special care was taken to reduce bias effects due to the weighting function, normalization, dead time and background corrections. The total uncertainty due to normalization, neutron flux and weighting function is 1.0%. An additional uncertainty of 0.5% results from the correction for self-shielding and multiple interaction events. Fluctuations due to resonance structures have been studied by complementary measurements at a 30m flight path station. The results reported in this work deviate systematically by more than 5% from the cross section that is recommended as a reference for astrophysical applications. They are about 2% lower compared to an evaluation of the 197Au(n, γ) cross section, which was based on a least squares fit of experimental data available in the literature prior to this work. The average capture cross section as a function of neutron energy has been parameterized in terms of average resonance parameters. Maxwellian average cross sections at different temperatures have been calculated.

  17. Missing'' 19/2 sup + states in sup 141 Pr and sup 143 Pm

    SciTech Connect

    Aziz, S.M.; Cottle, P.D.; Kemper, K.W. )

    1990-05-01

    A simple weak coupling model previously applied to the analysis of the yrast spectrum of {sup 143}Nd is extended to yrast spectra of odd-{ital A} {ital N}=82 and 83 isotopes of {ital Z}=58--61 nuclei. The model generally provides a good description of these spectra; however, yrast 19/2{sup +} states expected to arise in {sup 141}Pr and {sup 143}Pm from the coupling of {pi}{ital g}{sub 7/2} holes to the 6{sub 1}{sup +} states of the even-even cores are not observed experimentally. The absence of these states can be explained using a simple microscopic argument.

  18. Fission fragment angular distribution for the 19F+197Au fusion-fission reaction at near-barrier energies

    NASA Astrophysics Data System (ADS)

    Tripathi, R.; Sudarshan, K.; Sodaye, S.; Reddy, A. V.; Mahata, K.; Goswami, A.

    2005-04-01

    Angular distribution of fission fragments have been measured for 19F+197Au reaction at bombarding energies from 91 to 110 MeV. Fission fragment angular distributions have been calculated by transition state model with the transmission coefficients obtained using the coupled-channels theory. The calculated angular anisotropies are in good agreement with the experimental anisotropies. The experimental fission cross sections have also been reproduced on the basis of the coupled-channels theory. The results of angular distribution measurement do not show any significant contribution from quasifission as was reported in the literature based on the measurement of evaporation residues and mass distribution.

  19. 100-MeV proton beam intensity measurement by Au activation analysis using 197Au(p, pn)196Au and 197Au(p, p3n)194Au reactions

    NASA Astrophysics Data System (ADS)

    Mokhtari Oranj, Leila; Jung, Nam-Suk; Oh, Joo-Hee; Lee, Hee-Seock

    2016-05-01

    The proton beam intensity of a 100-MeV proton linac at the Korea Multi-purpose Accelerator Complex (KOMAC) was measured by an Au activation analysis using 197Au(p, pn)196Au and 197Au(p, p3n)194Au reactions to determine the accuracy and precision of beam intensity measurement using Gafchromic film dosimetry method. The target, irradiated by 100-MeV protons, was arranged in a stack consisting of Au, Al foils and Pb plates. The yields of produced radio-nuclei in Au foils were obtained by gamma-ray spectroscopy. The FLUKA code was employed to calculate the energy spectrum of protons onto the front surface of Au foils located at three different depth points of the target and also to investigate the condition of incident beam on the target. A good agreement was found between the beam intensity measurements using the activation analysis method at three different depth points of the target. An excellent agreement was also observed between the beam intensity measurements using the Au activation analysis method and the dosimetry method using Gafchromic film.

  20. Complete and incomplete fusion and emission of preequilibrium nucleons in the interaction of [sup 12]C with [sup 197]Au below 10 MeV/nucleon

    SciTech Connect

    Vergani, P.; Gadioli, E.; Vaciago, E.; Fabrici, E.; Gadioli Erba, E.; Galmarini, M. ); Ciavola, G.; Marchetta, C. )

    1993-10-01

    The excitation functions for production of nineteen isotopes of At, Po, Bi, Pb, and Tl in the interaction of [sup 12]C with [sup 197]Au between 57 and 97 MeV incident energy have been measured with the activation technique. The analysis of these data allows one to estimate the cross sections for complete fusion of [sup 12]C and incomplete fusion of [sup 8]Be and [alpha] fragments with gold, and shows the presence of preequilibrium emissions at incident energies only slightly higher than the Coulomb barrier acting between [sup 12]C and [sup 197]Au.

  1. Pauli blocking in the low-lying, low-spin states of {sup 141}Pr

    SciTech Connect

    Scheck, M.; Choudry, S. N.; Elhami, E.; McEllistrem, M. T.; Mukhopadhyay, S.; Orce, J. N.; Yates, S. W.

    2008-09-15

    The low-lying, low-spin levels of {sup 141}Pr were investigated using (n,n{sup '}{gamma}) techniques. Level energies, branching ratios, and tentative spin assignments for more than 100 states, linked by nearly 300 transitions, were obtained from two angular distributions (E{sub n}=2.0 and 3.0 MeV) and an excitation function measurement (E{sub n}=1.5-3.2 MeV). The application of the Doppler-shift attenuation method led to the determination of lifetimes. The obtained spectroscopic data provide insight into the wave functions of the states observed. A detailed analysis of the [2{sub 1}{sup +} x d{sub 5/2}] and [2{sub 1}{sup +} x g{sub 7/2}] multiplets provides the first quantitative evidence for Pauli blocking in a spherical odd-mass nucleus. The unpaired particle is used to probe the microscopic structure of the first 2{sup +} state of the adjacent core nuclei {sup 140}Ce and {sup 142}Nd.

  2. Mass and charge flow in the reaction 7.1 MeV/u197Au+63Cu

    NASA Astrophysics Data System (ADS)

    Jäckel, B.; Rox, A.; Esterlund, R. A.; Westmeier, W.; Knaack, M.; Patzelt, P.

    1991-12-01

    Mass-yield and angular-distribution data are presented for products from the reaction of 7.1 MeV/ μ 197Au with63Cu. With help from information derived from the latter, the former are classified into components corresponding to quasielastic transfer (580±80 mb), deep-inelastic transfer plus quasifission (1300±130 mb), fusionfission (≦195 mb), and sequential fission (195±45 mb). The fusion excitation function calculated with the Dynamic Capture model standard parameter set reproduces our deduced fusion-fission cross section well. Moreover, using this cross section as well as additional published data for the same reaction system, we extract an s-wave fusion-barrier shift (“extra push”) for this system of 35±7 MeV, which is in good agreement with the systematics derived from other fusion-barrier shifts which have been reported in the literature. Lastly, support is found for the Dissipative Diabatic Dynamics model prediction that dynamically-hindered fusion trajectories are reflected into quasielastic channels.

  3. Measurement of excitation functions in the reactions 197Au(11C, xn)208-xAt using a radioactive 11C beam

    PubMed

    Joosten; Powell; Guo; Haustein; Larimer; McMahan; Norman; O'Neil; Rowe; VanBrocklin; Wutte; Xu; Cerny

    2000-05-29

    A light-element radioactive ion-beam capability has been developed at the LBNL 88-Inch Cyclotron. The system is based on the coupled-cyclotrons method and utilizes short-lived species, e.g., 11C, 14O, 13N produced by (p,n) and (p,alpha) reactions at the LBNL Biomedical Isotope Facility Cyclotron. In a first experiment, 197Au(11C,xn)208-xAt excitation functions have been measured for energies ranging from the Coulomb barrier up to 110 MeV using a beam of 11C with intensities up to (1-2)x10(8) ions/sec on target. The results of this experiment are compared to measurements of 197Au(12C, xn)209-xAt excitation functions. PMID:10990868

  4. Two-particle rapidity correlations between relativistic particles in central collisions of ^{197}Au nuclei in emulsion at 11.6 A GeV/c

    NASA Astrophysics Data System (ADS)

    Abdurakhmanov, U. U.; Gulamov, K. G.; Navotny, V. Sh.

    2016-06-01

    It is shown that in central collisions of ^{197}Au nuclei with heavy emulsion nuclei at 11.6 AGeV/c two-particles pseudorapidity correlations for produced particles in terms of correlation functions demonstrate predominantly long-range behaviour in contrast to nucleon-nucleon interactions. The experimental data are compared with calculations based on the FRITIOF-M model and the model of independent emission of particles.

  5. Measurement of flux-weighted average cross sections for 197Au(γ, xn) reactions and isomeric yield ratios of 196m,gAu with bremsstrahlung

    NASA Astrophysics Data System (ADS)

    Naik, Haladhara; Kim, Guinyun; Kim, Kwangsoo; Zaman, Muhammad; Goswami, Ashok; Lee, Man Woo; Yang, Sung-Chul; Lee, Young-Ouk; Shin, Sung-Gyun; Cho, Moo-Hyun

    2016-04-01

    Photo-neutron cross sections of 197Au were experimentally determined for the bremsstrahlung end-point energies of 50, 60, and 70 MeV, by utilizing activation and off-line γ-ray spectrometric technique, using the 100 MeV electron linac at the Pohang Accelerator Laboratory (PAL), Pohang, Korea. The 197Au(γ, xn; x = 1- 6) reaction cross sections were calculated as a function of the bombarding photon energy by using the TALYS 1.6 computer code with default parameters. The flux-weighted average cross sections were obtained from the literature data and the theoretical values of TALYS 1.6 and TENDL-2014, for mono-energetic photons, and are found to be in good agreement with the present data. Isomeric yield ratios of 196m2,gAu from the 197Au(γ, n) reaction were also determined for the bremsstrahlung end-point energies of 50, 60, and 70 MeV, from the reaction cross sections of m2- and g-states, based on the present experimental data, and are found to be in good agreement with the theoretical values based on TALYS 1.6 and TENDL-2014.

  6. Gold nanoparticles production using reactor and cyclotron based methods in assessment of (196,198)Au production yields by (197)Au neutron absorption for therapeutic purposes.

    PubMed

    Khorshidi, Abdollah

    2016-11-01

    Medical nano-gold radioisotopes is produced regularly using high-flux nuclear reactors, and an accelerator-driven neutron activator can turn out higher yield of (197)Au(n,γ)(196,198)Au reactions. Here, nano-gold production via radiative/neutron capture was investigated using irradiated Tehran Research Reactor flux and also simulated proton beam of Karaj cyclotron in Iran. (197)Au nano-solution, including 20nm shaped spherical gold and water, was irradiated under Tehran reactor flux at 2.5E+13n/cm(2)/s for (196,198)Au activity and production yield estimations. Meanwhile, the yield was examined using 30MeV proton beam of Karaj cyclotron via simulated new neutron activator containing beryllium target, bismuth moderator around the target, and also PbF2 reflector enclosed the moderator region. Transmutation in (197)Au nano-solution samples were explored at 15 and 25cm distances from the target. The neutron flux behavior inside the water and bismuth moderators was investigated for nano-gold particles transmutation. The transport of fast neutrons inside bismuth material as heavy nuclei with a lesser lethargy can be contributed in enhanced nano-gold transmutation with long duration time than the water moderator in reactor-based method. Cyclotron-driven production of βeta-emitting radioisotopes for brachytherapy applications can complete the nano-gold production technology as a safer approach as compared to the reactor-based method. PMID:27524041

  7. Recoil studies of photonuclear reactions on natCu, natAg, natTa, and 197Au at intermediate energies

    NASA Astrophysics Data System (ADS)

    Fujiwara, I.; Haba, H.; Matsumura, H.; Sakamoto, K.; Miyamoto, Y.; Oura, Y.; Shibata, S.; Furukawa, M.

    1999-01-01

    The recoil properties of nuclides produced in the photonuclear reactions on natCu, natAg, natTa, and 197Au induced by bremsstrahlung of end-point energies (E o) of 250 to 1000 MeV have been investigated using the thick-target thick-catcher method. The obtained mean ranges of produced nuclides smoothly increase with an increase of the mass difference (ΔA) between products and target, and show E 0-independence at E 0≥600 MeV, reflecting the limiting behavior above (3, 3) resonance region. The mean kinetic energies, T, deduced from the mean ranges show the following two components; (1) (γ, xn) products by giant-resonance and/or quasi-deuteron resonance absorption, (2) (γ, xnyp) products by mainly (3, 3) resonance absorption. Slightly rapid increase of T was found around ΔA=15, 18, 24, and 25 for natCu, natAg, natTa and 197Au, respectively, reflecting a change in mechanism. Kinematic properties of the product nuclei were calculated by using the PICA (Photon-Induced Intranuclear Cascade Analysis) code. The T calculated by the PICA code at E 0=400 MeV well reproduced the experimental results of natCu, but the same calculation for natAg, natTa, and 197Au gave lower mean kinetic energies than the experimental results.

  8. Recoil studies of photonuclear reactions on natCu, natAg, natTa, and 197Au at intermediate energies

    NASA Astrophysics Data System (ADS)

    Fujiwara, I.; Haba, H.; Matsumura, H.; Sakamoto, K.; Miyamoto, Y.; Oura, Y.; Shibata, S.; Furukawa, M.

    1999-01-01

    The recoil properties of nuclides produced in the photonuclear reactions on natCu, natAg, natTa, and 197Au induced by bremsstrahlung of end-point energies ( E o) of 250 to 1000 MeV have been investigated using the thick-target thick-catcher method. The obtained mean ranges of produced nuclides smoothly increase with an increase of the mass difference (ΔA) between products and target, and show E 0-independence at E 0≥600 MeV, reflecting the limiting behavior above (3, 3) resonance region. The mean kinetic energies, T, deduced from the mean ranges show the following two components; (1) (γ, xn) products by giant-resonance and/or quasi-deuteron resonance absorption, (2) (γ, xnyp) products by mainly (3, 3) resonance absorption. Slightly rapid increase of T was found around ΔA=15, 18, 24, and 25 for natCu, natAg, natTa and 197Au, respectively, reflecting a change in mechanism. Kinematic properties of the product nuclei were calculated by using the PICA (Photon-Induced Intranuclear Cascade Analysis) code. The T calculated by the PICA code at E 0=400 MeV well reproduced the experimental results of natCu, but the same calculation for natAg, natTa, and 197Au gave lower mean kinetic energies than the experimental results.

  9. Dipole strength distributions of the stable odd-mass N=82 isotones {sup 139}La and {sup 141}Pr

    SciTech Connect

    Scheck, M.; Brentano, P. von; Fransen, C.; Linnemann, A.; Muecher, D.; Pietralla, N.; Scholl, C.; Werner, V.; Kneissl, U.; Kohstall, C.; Pitz, H. H.; Stedile, F.; Walter, S.; Yates, S. W.

    2007-04-15

    The low-lying dipole strength distributions of the odd-mass isotopes {sup 139}La and {sup 141}Pr were studied in nuclear resonance fluorescence experiments using bremsstrahlung beams. Excited states were observed at excitation energies up to 4 MeV. Spectroscopic information was obtained on excitation energies, decay widths, decay branching ratios, and transition probabilities. The states belonging to the [[2{sup +}(multiply-in-circle sign)3{sup -}](multiply-in-circle sign)particle/hole] coupling were a special focus, and the results are compared with other stable odd-mass nuclei at or near the N=82 shell closure.

  10. {sup 63}Cu and {sup 197}Au nuclear quadrupole moments from four-component relativistic density-functional calculations using correct long-range exchange

    SciTech Connect

    Thierfelder, Christian; Schwerdtfeger, Peter; Saue, Trond

    2007-09-15

    The electric field gradient in late transition metal compounds is incorrectly determined by most density functionals. We show that the coupling of short-range density functional based with long-range wave function based methods using a reparametrization of the Coulomb-attenuated Becke three-parameter Lee-Yang-Parr approximation gives reliable results for the electric field gradients of copper and gold for a series of compounds. This results in nuclear quadrupole moments of -0.208 b for {sup 63}Cu and +0.526 b for {sup 197}Au in good agreement with experimental values of -0.220(15) and +0.547(16)b, respectively.

  11. Perturbation on hyperfine-enhanced 141Pr nuclear spin dynamics associated with antiferroquadrupolar order in PrV2Al20

    NASA Astrophysics Data System (ADS)

    Ito, T. U.; Higemoto, W.; Sakai, A.; Tsujimoto, M.; Nakatsuji, S.

    2015-09-01

    The nature of multipolar order and hyperfine-enhanced (HE) 141Pr nuclear spin dynamics in PrV2Al20 was investigated using the muon spin relaxation technique. No explicit sign of time-reversal symmetry breaking was found below the multipolar order temperature TQ˜0.6 K in a zero applied field as anticipated on the basis of the antiferroquadrupolar (AFQ) order picture proposed by Sakai and Nakatsuji [J. Phys. Soc. Jpn. 80, 063701 (2011), 10.1143/JPSJ.80.063701]. Further evidence of the nonmagnetic ground state was obtained from the observation of HE 141Pr nuclear spin fluctuations in the MHz scale. A marked increase in the muon spin-lattice relaxation rate (1 /T1 ,μ) was observed below 1 K with decreasing temperature, which was attributed to the perturbation on the HE 141Pr nuclear spin dynamics associated with the development of AFQ correlations. The longitudinal field dependence of 1 /T1 ,μ revealed that the enhanced 141Pr nuclear spin accidentally has an effective gyromagnetic ratio close to that of the muon.

  12. Preresidue'' light charged particles from [sup 28]Si+[sup 165]Ho, [sup 16]O+[sup 197]Au, and [sup 16]O+[sup 208]Pb fusion

    SciTech Connect

    Fineman, B.J.; Brinkmann, K.; Caraley, A.L.; Gan, N.; McGrath, R.L.; Velkovska, J. )

    1994-10-01

    Proton and [alpha]-particle spectral shapes and multiplicities have been measured in coincidence with evaporation residues from 145 to 220 MeV [sup 28]Si+[sup 165]Ho and 115 and 140 MeV [sup 16]O+[sup 197]Au,[sup 208]Pb fusion reactions. Evaporation residues were separated using an electrostatic deflector and detected with large area surface barrier detectors. Light charged particles were detected at forward and backward angles with 14 single NaI detectors. In the context of the statistical model, the charged particle spectra provide information about the shapes and level densities of the emitting systems. Deformed emitters are inferred, and to a varying degree, an energy-dependent level density parameter is compatible with the data in each of the three cases. Implications for current fusion and fission dynamics studies are discussed.

  13. Formation of a necklike structure in {sup 35}Cl+{sup 12}C and {sup 197}Au reactions at 43 MeV/nucleon

    SciTech Connect

    Larochelle, Y.; Gingras, L.; Beaulieu, L.; Qian, X.; Saddiki, Z.; Djerroud, B.; Dore, D.; Laforest, R.; Roy, R.; Samri, M.; St-Pierre, C.; Ball, G.C.; Bowman, D.R.; Galindo-Uribarri, A.; Hagberg, E.; Horn, D.; Lopez, J.A.; Robinson, T.

    1997-04-01

    The experimental signature of the formation of a necklike structure, with a velocity between that of the projectilelike emitter and that of the targetlike emitter, is investigated with the same beam and experimental setup for targets lighter and heavier than the projectile. The reactions are {sup 35}Cl on {sup 12}C and on {sup 197}Au at 43 MeV/nucleon. Particle velocity distributions are compared with two-source statistical simulations and the presence of a necklike structure is inferred from the data. In the second part of the paper, dynamical model simulations with the formation of a necklike structure are presented for the {sup 35}Cl+{sup 12}C system at 43 MeV/nucleon. {copyright} {ital 1997} {ital The American Physical Society}

  14. Decay analysis of pre-actinide and trans-actinide nuclei formed using various projectiles on a 197Au target at ECN*=60 MeV

    NASA Astrophysics Data System (ADS)

    Grover, Neha; Kaur, Gurvinder; Sharma, Manoj K.

    2016-01-01

    The collective clusterization approach of the dynamical cluster decay model (DCM) has been applied to study the decay of odd mass nuclei 223Pa*, 215Fr*, 227Np*, and 233Am*, which are formed in heavy-ion-induced reactions. The aim of this study is to investigate the decay pattern and related behavior of these heavy mass nuclei formed in four distinct reactions involving different projectiles (with mass A =18 -36 ) induced on 197Au target nucleus. Further, in order to analyze the role of deformations, the calculations have been done by considering spherical choice of fragmentation as well as with inclusion of quadrupole (β2) deformation. For the heavy mass region, with fission being the dominant decay mode, an attempt has been made to investigate the effect of projectile mass in reference to fission decay patterns of the pre-actinide 215Fr* nucleus and the trans-actinide nuclei 227Np* 223Pa*, 223Am* and formed at common excitation energy, ECN*=60 MeV . Besides this, the shell closure effects and the role of orientation have been explored, which suggest the presence of a noncompound nucleus process such as quasifission (QF) for the odd mass nuclei under consideration. For both the compound nucleus and the noncompound nucleus processes, the results obtained using DCM are found to have nice agreement with experimental observations. The isotopic and isobaric analysis is also worked out so as to have a comprehensive idea about the dynamics involved.

  15. Study of the A(e,e'$\\pi^+$) Reaction on $^1$H, $^2$H, $^{12}$C, $^{27}$Al, $^{63}$Cu and $^{197}$Au

    SciTech Connect

    Qian, X; Clasie, B; Arrington, J; Asaturyan, R; Benmokhtar, F; Boeglin, W; Bosted, P; Bruell, A; Christy, M E; Chudakov, E; Dalton, M M; Daniel, A; Day, D; Dutta, D; El Fassi, L; Ent, R; Fenker, H C; Ferrer, J; Fomin, N; Gao, H; Garrow, K; Gaskell, D; Gray, C; Huber, G M; Jones, M K; Kalantarians, N; Keppel, C E; Kramer, K; Li, Y; Liang, Y; Lung, A F; Malace, S; Markowitz, P; Matsumura, A; Meekins, D G; Mertens, T; Miyoshi, T; Mkrtchyan, H; Monson, R; Navasardyan, T; Niculescu, G; Niculescu, I; Okayasu, Y; Opper, A K; Perdrisat, C; Punjabi, V; Rauf, A W; Rodriquez, V M; Rohe, D; Seely, J; Segbefia, E; Smith, G R; Sumihama, M; Tadevosyan, V; Tang, L; Villano, A; Vulcan, W F; Wesselmann, F R; Wood, S A; Yuan, L; Zheng, X

    2010-05-01

    Cross sections for the p($e,e'\\pi^{+}$)n process on $^1$H, $^2$H, $^{12}$C, $^{27}$Al, $^{63}$Cu and $^{197}$Au targets were measured at the Thomas Jefferson National Accelerator Facility (Jefferson Lab) in order to extract the nuclear transparencies. Data were taken for four-momentum transfers ranging from $Q^2$=1.1 to 4.8 GeV$^2$ for a fixed center of mass energy of $W$=2.14 GeV. The ratio of $\\sigma_L$ and $\\sigma_T$ was extracted from the measured cross sections for $^1$H, $^2$H, $^{12}$C and $^{63}$Cu targets at $Q^2$ = 2.15 and 4.0 GeV$^2$ allowing for additional studies of the reaction mechanism. The experimental setup and the analysis of the data are described in detail including systematic studies needed to obtain the results. The results for the nuclear transparency and the differential cross sections as a function of the pion momentum at the different values of $Q^2$ are presented. Global features of the data are discussed and the data are compared with the results of model calculations for the p($e,e'\\pi^{+}$)n reaction from nuclear targets.

  16. Validation of absolute axial neutron flux distribution calculations with MCNP with 197Au(n,γ)198Au reaction rate distribution measurements at the JSI TRIGA Mark II reactor.

    PubMed

    Radulović, Vladimir; Štancar, Žiga; Snoj, Luka; Trkov, Andrej

    2014-02-01

    The calculation of axial neutron flux distributions with the MCNP code at the JSI TRIGA Mark II reactor has been validated with experimental measurements of the (197)Au(n,γ)(198)Au reaction rate. The calculated absolute reaction rate values, scaled according to the reactor power and corrected for the flux redistribution effect, are in good agreement with the experimental results. The effect of different cross-section libraries on the calculations has been investigated and shown to be minor. PMID:24316530

  17. Excitation energies and temperatures of hot nuclei produced in the reactions of {sup 63}Cu+{sup 197}Au at 35A MeV

    SciTech Connect

    Wada, R.; Tezkratt, R.; Hagel, K.; Haddad, F.; Kolomiets, A.; Lou, Y.; Li, J.; Shimooka, M.; Shlomo, S.; Utley, D.; Xiao, B.; Mdeiwayeh, N.; Natowitz, J.B.; Majka, Z.; Cibor, J.; Kozik, T.; Sosin, Z.

    1997-01-01

    Observations of heavy remnants emitted at forward angles with high velocities and high associated particle multiplicities have been used to select central collisions of 35A MeV {sup 63}Cu with {sup 197}Au. The data indicate that these remnants, both fission fragments and evaporation residuelike products, result from the deexcitation of nuclei with A{approximately}225{endash}240 having excitation energies of {approximately} 800{endash}1300 MeV. Similar particle multiplicities are observed for both evaporative and fission decay channels. Modeling the results with hybrid codes which treat entrance channel dynamics followed by sequential statistical decay requires the inclusion of some delay in the fission channel to produce heavy remnants with mass A{ge}130, but the trend of the predicted velocities of these heavy remnants is different from that of the experiments. Calculations with a dynamic model based on the molecular dynamics approach have also been performed and lead to similar results. He and Li isotope yield ratios and the apparent temperatures derived from those ratios are similar to those previously reported for excited nuclei in this mass region. Temperatures derived from other yield ratios are also similar once a self-consistent treatment, taking into account population and decay of known excited states, is applied. The derived temperatures show little variation with excitation energy, suggesting that a limiting temperature may be reached at relatively low excitation energy, although the interpretation of this result and the determination of the actual initial value of this temperature is model dependent. Comments on the application of the double isotope yield ratio technique to extraction of the nuclear caloric curve are made. {copyright} {ital 1997} {ital The American Physical Society}

  18. Magnetic moments of the isomeric states of /sup 141/Pr and /sup 143/Pm and the paramagnetism of promethium and praseodymium

    SciTech Connect

    Gorbachev, B.I.; Levon, A.I.; Nemets, O.F.; Fedotkin, S.N.; Stepanenko, V.A.

    1984-07-01

    The g-factors of the 11/2/sup -/ and 15/2/sup +/ isomeric states of the /sup 141/Pr and /sup 143/Pm nuclei (Tables I and II) have been measured by the method of differential and integrated perturbed angular distribution. The parametric corrections were determined for /sup 143/Pm from the measured temperature dependence g..beta..(T). The relaxation times have been measured for nuclear states aligned in beam reactions, metal targets, and targets made of La and Pr oxides. The results are analyzed in terms of the quasiparticle-phonon model with allowance for the spin-multipole interaction.

  19. Theoretical investigation of shape parametrization’s effects on characteristics of fission fragments in 18O-induced fission of 154Sm, 197Au, 238U and 246Cm

    NASA Astrophysics Data System (ADS)

    Pahlavani, M. R.; Mirfathi, S. M.

    2015-06-01

    The multi-dimensional Langevin equations are employed to investigate mass and energy distributions of fission fragments. The calculations have been performed with two different shape classes of parametrization, namely Funny Hills and Cassinian Ovaloids. It was shown that inclusion of the Funny Hills parameterizations in the dynamical model produced considerable increase in neutron multiplicity as compared with available experimental data for 18O-induced fission of 154Sm, 197Au, 238U and 246Cm. The proposed shape-dependent multi-dimensional dynamical model reproduces well experimental data for mass distribution, neutron multiplicity and average kinetic energy of fission fragments over a wide range of mass-energy regions.

  20. 4{pi} studies of the 1.8{endash}4.8 GeV {sup 3}He+{sup nat}Ag, {sup 197}Au reactions. I. Energy deposition

    SciTech Connect

    Morley, K.B.; Kwiatkowski, K.; Bracken, D.S.; Renshaw Foxford, E.; Viola, V.E.; Woo, L.W.; Yoder, N.R.; Legrain, R.; Pollacco, E.C.; Volant, C.; Korteling, R.G.; Breuer, H.; Brzychczyk, J.

    1996-08-01

    The Indiana Silicon Sphere 4{pi} detector has been used to measure light-charged particles and intermediate-mass fragments (IMFs) emitted in the 18{endash}4.8 GeV {sup 3}He+{sup nat}Ag, {sup 197}Au reactions. Ejectile multiplicity and total event kinetic energy distributions scale systematically with projectile energy and target mass, except for the {sup nat}Ag target at 3.6 and 4.8 GeV. For this system, a saturation in deposition energy is indicated by the data, suggesting the upper projectile energy for stopping has been reached. Maximum deposition energies of {approximately}950 MeV for the {sup nat}Ag target and {approximately}1600 MeV for the {sup 197}Au target are inferred from the data. The results also demonstrate the importance of accounting for fast cascade processes in defining the excitation energy of the targetlike residue. Correlations between various observables and the average IMF multiplicity indicate that the total thermal energy and total observed charge provide useful gauges of the excitation energy of the fragmenting system. Comparison of the experimental distributions with intranuclear cascade predictions shows qualitative agreement. {copyright} {ital 1996 The American Physical Society.}

  1. Thermal neutron calibration of a tritium extraction facility using the /sup 6/Li(n,t)/sup 4/He//sup 197/Au(n,. gamma. )/sup 198/Au cross section ratio for standardization

    SciTech Connect

    Bretscher, M.M.; Smith, D.L.

    1980-08-01

    Absolute tritium activities in a neutron-activated metallic lithium samples have been measured by liquid scintillation methods to provide data needed for the determination of capture-to-fission ratios in fast breeder reactor spectra and for recent measurements of the /sup 7/Li(n,n't)/sup 4/He cross section. The tritium extraction facility used for all these experiments has now been calibrated by measuring the /sup 6/Li(n,t)/sup 4/He//sup 197/Au/n,..gamma..)/sup 198/Au activity ratio for thermal neutrons and comparing the result with the well-known cross sections. The calculated-to-measured activity ratio was found to be 1.033 +- 0.018. 2 figures, 20 tables.

  2. Angular distributions of target fragments from the reactions of 292 MeV - 25. 2 GeV /sup 12/C with /sup 197/Au and /sup 238/U

    SciTech Connect

    Morita, Y.

    1983-05-20

    Angular distributions of target fragments from the reactions of /sup 12/C with /sup 197/Au and /sup 238/U were measured at projectile energies of 292 MeV, 1.0 GeV, 3.0 GeV, 12.0 GeV and 25.2 GeV. The angular distributions of the /sup 197/Au target fragments were all forwardly peaked. Extensively forward peaked angular distributions were observed at the non-relativistic projectile energies (292 MeV, 1.0 GeV). No obvious differences were observed in the angular distributions at the different relativistic projectile energies of 3.0 GeV, 12.0 GeV and 25.2 GeV. The characteristic angular distribution pattern from the relativistic projectile energy experiments was also observed in the non-relativistic energy experiments. Maximum degree of forward-peaking in the angular distributions at each projectile energy was observed at the product mass number (A) around 190 from the 292 MeV projectile energy, at A=180 from 1.0 GeV and at A=175 from 3.0 GeV and 12.0 GeV. In general, two different types of angular distributions were observed in the relativistic projectile energy experiments with the /sup 238/U target. Isotropic angular distributions were observed for the fission product nuclides. The angular distributions of the fission products at the intermediate (292 MeV) energy showed slightly forward- peaked angular distributions. Because of the long projectile-target interaction time in the primary nuclear reaction, larger momentum was transferred from the projectile to the target nucleus. Steep forward-peaked angular distributions were also observed with the /sup 238/U target.

  3. Absolute NMR shielding scales and nuclear spin–rotation constants in {sup 175}LuX and {sup 197}AuX (X = {sup 19}F, {sup 35}Cl, {sup 79}Br and {sup 127}I)

    SciTech Connect

    Demissie, Taye B. Komorovsky, Stanislav; Repisky, Michal; Ruud, Kenneth; Jaszuński, Michał

    2015-10-28

    We present nuclear spin–rotation constants, absolute nuclear magnetic resonance (NMR) shielding constants, and shielding spans of all the nuclei in {sup 175}LuX and {sup 197}AuX (X = {sup 19}F, {sup 35}Cl, {sup 79}Br, {sup 127}I), calculated using coupled-cluster singles-and-doubles with a perturbative triples (CCSD(T)) correction theory, four-component relativistic density functional theory (relativistic DFT), and non-relativistic DFT. The total nuclear spin–rotation constants determined by adding the relativistic corrections obtained from DFT calculations to the CCSD(T) values are in general in agreement with available experimental data, indicating that the computational approach followed in this study allows us to predict reliable results for the unknown spin–rotation constants in these molecules. The total NMR absolute shielding constants are determined for all the nuclei following the same approach as that applied for the nuclear spin–rotation constants. In most of the molecules, relativistic effects significantly change the computed shielding constants, demonstrating that straightforward application of the non-relativistic formula relating the electronic contribution to the nuclear spin–rotation constants and the paramagnetic contribution to the shielding constants does not yield correct results. We also analyze the origin of the unusually large absolute shielding constant and its relativistic correction of gold in AuF compared to the other gold monohalides.

  4. Absolute NMR shielding scales and nuclear spin-rotation constants in (175)LuX and (197)AuX (X = (19)F, (35)Cl, (79)Br and (127)I).

    PubMed

    Demissie, Taye B; Jaszuński, Michał; Komorovsky, Stanislav; Repisky, Michal; Ruud, Kenneth

    2015-10-28

    We present nuclear spin-rotation constants, absolute nuclear magnetic resonance (NMR) shielding constants, and shielding spans of all the nuclei in (175)LuX and (197)AuX (X = (19)F, (35)Cl, (79)Br, (127)I), calculated using coupled-cluster singles-and-doubles with a perturbative triples (CCSD(T)) correction theory, four-component relativistic density functional theory (relativistic DFT), and non-relativistic DFT. The total nuclear spin-rotation constants determined by adding the relativistic corrections obtained from DFT calculations to the CCSD(T) values are in general in agreement with available experimental data, indicating that the computational approach followed in this study allows us to predict reliable results for the unknown spin-rotation constants in these molecules. The total NMR absolute shielding constants are determined for all the nuclei following the same approach as that applied for the nuclear spin-rotation constants. In most of the molecules, relativistic effects significantly change the computed shielding constants, demonstrating that straightforward application of the non-relativistic formula relating the electronic contribution to the nuclear spin-rotation constants and the paramagnetic contribution to the shielding constants does not yield correct results. We also analyze the origin of the unusually large absolute shielding constant and its relativistic correction of gold in AuF compared to the other gold monohalides. PMID:26520517

  5. Breakup of the projectile in [sup 16]O-induced reactions on [sup 27]Al, [sup 58]Ni, and [sup 197]Au targets around 100 MeV/nucleon

    SciTech Connect

    Badala, A.; Barbera, R.; Palmeri, A.; Pappalardo, G.S. ); Riggi, F. Dipartimento di Fisica dell'Universita di Catania, Corso Italia 57, 95129 Catania )

    1993-08-01

    The spatial correlation among the four He ions coming from the disassembly of the [sup 16]O projectile on [sup 27]Al, [sup 58]Ni, and [sup 197]Au targets has been studied at 94 MeV/nucleon. Charged particles have been detected by a multielement array of plastic scintillators covering the angular domain between 3[degree] and 150[degree]. Standard relativistic kinematics has been used to reconstruct the excitation energy of the primary projectilelike nucleus ([ital E][sub PLN][sup *]). Mean values of this quantity are found independent of the target mass and the comparison with existing similar data taken at lower bombarding energies shows a saturation of [ital E][sub PLN][sup *] around 3 MeV/nucleon. An event-by-event analysis has been performed in order to study the distributions of some global variables such as coplanarity, sphericity, and relative angle, helpful in the understanding of the topological characteristics of the process and in the evaluation of its time scale. Experimental data have also been compared with the results of Monte Carlo simulations based on different reaction mechanisms and it is possible to conclude that sequential emission of the fragments is preferred.

  6. Absolute photofission cross section of sup 197 Au, @Pb, sup 209 Bi, sup 232 Th, sup 238 U, and sup 235 U nuclei by 69-MeV monochromatic and polarized photons

    SciTech Connect

    Martins, J.B.; Moreira, E.L.; Tavares, O.A.P.; Vieira, J.L. Centro Brasileiro de Pesquisas Fisicas-CBPF, Rua Dr. Xavier Sigaud 150, 22290 Rio de Janeiro-RJ, ); Casano, L.; D'Angelo, A.; Schaerf, C. Istituto Nazionale di Fisica Nucleare-INFN, Sezione di Roma 2, Roma, ); Terranova, M.L. Istituto Nazionale di Fisica Nucleare-INFN, Sezione di Roma 2, Roma, Italy); Babusci, D. ); Girolami, B. Istituto Nazionale di Fisica Nuclea

    1991-07-01

    Absolute cross-section measurements for the photofission reactions of {sup 197}Au, {sup nat}Pb, {sup 209}Bi, {sup 232}Th, {sup 238}U, and {sup 235}U nuclei have been performed at an incident photon energy of 69 MeV using monochromatic and polarized photon beams and dielectric fission-track detectors. Nuclear fissility values have been obtained and results are in agreement with those from other laboratories, although in some cases discrepancies are observed between one other. For nuclei in the region of the actinides the fissility result is {approx gt}0.4, while for Au, Pb, and Bi nuclei it only is {similar to}10{sup {minus}3}--10{sup {minus}2}. Results have been interpreted in terms of the primary Levinger's quasideuteron nuclear photoabsorption followed by a mechanism of evaporation-fission competition for the excited nuclei. Shell effects have been taken into account, and they are clearly manifested when fissility is evaluated. The influence of photon polarization on photofission of {sup 238}U also has been investigated, and results have shown isotropy in the fragment azimuthal distribution.

  7. Absolute NMR shielding scales and nuclear spin-rotation constants in 175LuX and 197AuX (X = 19F, 35Cl, 79Br and 127I)

    NASA Astrophysics Data System (ADS)

    Demissie, Taye B.; Jaszuński, Michał; Komorovsky, Stanislav; Repisky, Michal; Ruud, Kenneth

    2015-10-01

    We present nuclear spin-rotation constants, absolute nuclear magnetic resonance (NMR) shielding constants, and shielding spans of all the nuclei in 175LuX and 197AuX (X = 19F, 35Cl, 79Br, 127I), calculated using coupled-cluster singles-and-doubles with a perturbative triples (CCSD(T)) correction theory, four-component relativistic density functional theory (relativistic DFT), and non-relativistic DFT. The total nuclear spin-rotation constants determined by adding the relativistic corrections obtained from DFT calculations to the CCSD(T) values are in general in agreement with available experimental data, indicating that the computational approach followed in this study allows us to predict reliable results for the unknown spin-rotation constants in these molecules. The total NMR absolute shielding constants are determined for all the nuclei following the same approach as that applied for the nuclear spin-rotation constants. In most of the molecules, relativistic effects significantly change the computed shielding constants, demonstrating that straightforward application of the non-relativistic formula relating the electronic contribution to the nuclear spin-rotation constants and the paramagnetic contribution to the shielding constants does not yield correct results. We also analyze the origin of the unusually large absolute shielding constant and its relativistic correction of gold in AuF compared to the other gold monohalides.

  8. Exclusive studies of 130-270 MeV {sup 3}He- and 200-MeV proton-induced reactions on {sup 27}Al, {sup nat}Ag, and {sup 197}Au

    SciTech Connect

    Ginger, D. S.; Kwiatkowski, K.; Wang, G.; Hsi, W.-C.; Hudan, S.; Cornell, E.; Souza, R. T. de; Viola, V. E.; Korteling, R. G.

    2008-09-15

    Exclusive light-charged-particle and IMF spectra have been measured with the ISiS detector array for bombardments of {sup 27}Al, {sup nat}Ag, and {sup 197}Au nuclei with 130-270-MeV {sup 3}He and 200-MeV protons. The results are consistent with previous interpretations based on inclusive data that describe the global yield of complex fragments in terms of a time-dependent process. The emission mechanism for energetic nonequilibrium fragments observed at forward angles with momenta up to twice the beam momentum is also investigated. This poorly understood mechanism, for which the angular distributions indicate formation on a time scale comparable to the nuclear transit time, are accompanied primarily by thermal-like emissions. The data are most consistent with a schematic picture in which nonequilibrium fragments are formed in a localized region of the target nucleus at an early stage in the energy-dissipation process, where the combined effects of high energy density and Fermi motion produce the observed suprathermal spectra.

  9. Effects of in-medium cross sections and optical potential on thermal-source formation in p+{sup 197}Au reactions at 6.2-14.6 GeV/c

    SciTech Connect

    Turbide, S.; Beaulieu, L.; Roy, R.; Danielewicz, P.; Huang, R.; Lynch, W.G.; Tsang, M.B.; Xi, H.; Viola, V.E.; Kwiatkowski, K.; Hsi, W.-C.; Wang, G.; Lefort, T.; Bracken, D.S.; Cornell, E.; Ginger, D.S.; Breuer, H.; Gimeno-Nogues, F.; Ramakrishnan, E.; Rowland, D.

    2004-07-01

    Effects of in-medium cross sections and of optical potential on preequilibrium emission and on formation of a thermal source are investigated by comparing the results of transport simulations with experimental results from the p+{sup 197}Au reaction at 6.2-14.6 GeV/c. The employed transport model includes light-composite-particle production and allows for inclusion of in-medium particle-particle cross-section reduction and of momentum dependence in the particle optical potentials. Compared to the past, the model incorporates improved parametrizations of elementary high-energy processes. The simulations indicate that the majority of energy deposition occurs during the first 25 fm/c of a reaction. This is followed by a preequilibrium emission and readjustment of system density and momentum distribution toward an equilibrated system. Within different variants of calculations, the best agreement with data, on the d/p and t/p yield ratios and on the residue mass and charge numbers, is obtained at the time of about 65 fm/c from the start of a reaction, for simulations employing reduced in-medium cross sections and momentum-dependent optical potentials. By that time, the preequilibrium nucleon and cluster emission, as well as mean field readjustments, drive the system to a state of depleted average density, {rho}/{rho}{sub 0}{approx}1/4-1/3 for central collisions, and low-to-moderate excitation, i.e., the region of nuclear liquid-gas phase transition.

  10. New quaternary arsenide oxides with square planar coordination of gold(I) - structure, (197)Au Mössbauer spectroscopic, XANES and XPS characterization of Nd10Au3As8O10 and Sm10Au3As8O10.

    PubMed

    Bartsch, Timo; Niehaus, Oliver; Johrendt, Dirk; Kobayashi, Yasuhiro; Seto, Makoto; Abdala, Paula M; Bartsch, Manfred; Zacharias, Helmut; Hoffmann, Rolf-Dieter; Gerke, Birgit; Rodewald, Ute Ch; Pöttgen, Rainer

    2015-03-28

    The quaternary gold(I) arsenide oxides Nd10Au3As8O10 and Sm10Au3As8O10 were synthesized in sealed quartz ampoules from the rare earth (RE) elements, their appropriate sesquioxides, arsenic, arsenic(III) oxide and finely dispersed gold at maximum annealing temperatures of 1223 K. Both structures were refined from X-ray single crystal diffractometer data at room temperature and at 90 K. Nd10Au3As8O10 and Sm10Au3As8O10 crystallize with a new structure type that derives from the BaAl4 structure through distortions and formation of ordered vacancies. The structures consist of stacked polycationic [RE10O10](10+) layers with oxygen in tetrahedral rare earth coordination and polyanionic [Au(I)3(As2)4](10-) layers with gold in square planar or rectangular planar coordination of four arsenic dumbbells (255 pm As1-As2). In contrast to the well known ionic rare earth oxide layers, the gold arsenide layers rather show covalent bonding and account for the metallic nature of these two new arsenide oxides. This is confirmed by electronic structure calculations and resistivity measurements. The oxidation state of gold was investigated by (197)Au Mössbauer, X-ray absorption near edge structure (XANES) and photoelectron (XPS) spectroscopy. Due to missing comparative gold arsenide compounds, the monovalent gold phosphide oxides RE2AuP2O were measured for comparison. The XANES measurements additionally comprise monovalent gold arsenides REAuAs2. The XPS study contains BaAuAs as reference compound instead. Combination of all data clearly indicates Au(I), which was not observed in square planar coordination up to now. Temperature dependent magnetic susceptibility data show Curie-Weiss paramagnetism for Nd10Au3As8O10 and no magnetic ordering down to 2.5 K. Sm10Au3As8O10 shows the typical Van Vleck type paramagnetism for samarium compounds along with a transition to an antiferromagnetically ordered state at TN = 8.6 K. PMID:25716906

  11. Heating {sup 197}Au nuclei with 8 GeV antiproton and {pi}- beams.

    SciTech Connect

    Back, B.; Beaulieu, L.; Breuer, H.; Gushue, S.; Hsi, W.-C.; Korteling, R. G.; Kwiatkowski, K.; Laforest, R.; Lefort, T.; Martin, E.; Pienkowski, L.; Ramakrishnan, E.; Remsberg, L. P.; Viola, V. E.

    1999-05-03

    This contribution stresses results recently obtained from experiment E900 performed at the Brookhaven AGS accelerator with 8 GeV/c antiproton and negative pion beams using the Indiana Silicon Sphere detector array. An investigation of the reaction mechanism is presented, along with source characteristics deduced from a two-component fit to the spectra. An enhancement of deposition energy with the antiproton beam with respect to the pion beam is observed. The results are qualitatively consistent with predictions of an intranuclear cascade code.

  12. Exclusive studies of angular distributions in GeV hadron-induced reactions with {sup 197}Au

    SciTech Connect

    Hsi, W.; Kwiatkowski, K.; Wang, G.; Bracken, D.S.; Cornell, E.; Ginger, D.S.; Viola, V.E.; Korteling, R.G.; Morley, K.B.; Huang, R.; Lynch, W.G.; Tsang, M.B.; Xi, H.; Gimeno-Nogues, F.; Ramakrishnan, E.; Rowland, D.; Yennello, S.J.; Breuer, H.; Gushue, S.; Remsberg, L.P.; Botvina, A.; Friedman, W.A.

    1999-09-01

    Exclusive studies of angular distributions for intermediate-mass fragments (IMFs) produced in GeV hadron-induced reactions have been performed with the Indiana Silicon Sphere (ISiS) 4{pi} detector array. Special emphasis has been given to understanding the origin of sideways peaking, which becomes prominent in the angular distributions for beam momenta above about 10 GeV/c. Both the magnitude of the effect and the peak angle increase as a function of fragment multiplicity and charge. When gated on IMF kinetic energy, the angular distributions evolve from forward-peaked to near isotropy as the fragment kinetic energy decreases. Fragment-fragment angular-correlation analyses show no obvious evidence for a dynamic mechanism that might signal shock wave effects or the breakup of exotic geometric shapes such as bubbles or toroids. Moving-source and intranuclear cascade simulations suggest that the observed sideways peaking is of kinematic origin, arising from significant transverse momentum imparted to the heavy recoil nucleus during the fast cascade stage of the collision. A two-step cascade and statistical multifragmentation calculation is consistent with this assumption. {copyright} {ital 1999} {ital The American Physical Society}

  13. Exclusive studies of angular distributions in GeV hadron-induced reactions with [sup 197]Au

    SciTech Connect

    Hsi, W.; Kwiatkowski, K.; Wang, G.; Bracken, D.S.; Cornell, E.; Ginger, D.S.; Viola, V.E. ); Korteling, R.G. V5A I56); Morley, K.B. ); Huang, R.; Lynch, W.G.; Tsang, M.B.; Xi, H. ); Gimeno-Nogues, F.; Ramakrishnan, E.; Rowland, D.; Yennello, S.J. ); Breuer, H. ); Gushue, S.; Remsberg, L.P. ); Botvin

    1999-09-01

    Exclusive studies of angular distributions for intermediate-mass fragments (IMFs) produced in GeV hadron-induced reactions have been performed with the Indiana Silicon Sphere (ISiS) 4[pi] detector array. Special emphasis has been given to understanding the origin of sideways peaking, which becomes prominent in the angular distributions for beam momenta above about 10 GeV/c. Both the magnitude of the effect and the peak angle increase as a function of fragment multiplicity and charge. When gated on IMF kinetic energy, the angular distributions evolve from forward-peaked to near isotropy as the fragment kinetic energy decreases. Fragment-fragment angular-correlation analyses show no obvious evidence for a dynamic mechanism that might signal shock wave effects or the breakup of exotic geometric shapes such as bubbles or toroids. Moving-source and intranuclear cascade simulations suggest that the observed sideways peaking is of kinematic origin, arising from significant transverse momentum imparted to the heavy recoil nucleus during the fast cascade stage of the collision. A two-step cascade and statistical multifragmentation calculation is consistent with this assumption. [copyright] [ital 1999] [ital The American Physical Society

  14. Fragment charge and energy distributions in the 1.8-4.8 GeV {sup 3}He + {sup nat}Ag, {sup 197}Au reactions

    SciTech Connect

    Bracken, D.S.; Foxford, E.R.; Kwiatkowski, K.

    1995-10-01

    Moving source fits have been performed for IMFs as a function of observables related to collision violence in the 1.8-4.8 GeV {sup 3}He +{sup nat}Ag, {sup l97}Au reactions. The systematic behavior of the source properties and fragment charge distributions will be reviewed. The evolution of the spectral Coulomb parameters provides evidence for nuclear expansion prior to multifragmentation, suggesting a breakup density of p/p{sub o} {approximately} 1/3. The charge distributions will be examined in terms of power-law fits and moment analyses.

  15. Statistical and microscopic description of energetic products in the reactions induced by sup 16 O on sup 27 Al, sup 58 Ni, and sup 197 Au at 94 MeV/nucleon

    SciTech Connect

    Badala, A.; Barbera, R.; Bonasera, A. ); Di Toro, M. Dipartimento di Fisica, Universita di Catania, Corso Italia 57, I-95129 Catania ); Palmeri, A.; Pappalardo, G.S. ); Riggi, F.; Russo, G. Dipartimento di Fisica, Universita di Catania, Corso Italia 57, I-95129 Catania ); Bizard, G.; Durand, D.; Laville, J.L. )

    1991-01-01

    Protons and charged pions have been detected at 70{degree}, 90{degree}, and 120{degree} in the reaction induced by {sup 16}O on various targets at 94 MeV/nucleon incident energy. Measured energy spectra are analyzed in terms of statistical emission from equilibrated sources in a participant-spectator picture. Microscopic dynamical calculations based on the Boltzmann-Nordheim-Vlasov equation are also performed. Experimental data are well reproduced by both models.

  16. Oregon State University nuclear chemistry progress report, August 1, 1989--August 1, 1990

    SciTech Connect

    Loveland, W.D.

    1990-08-01

    This report discusses the following topics: the elements beyond uranium; the interaction of 21 MeV/nucleon {sup 129}Xe with {sup 197}Au; the interaction of 93 MeV/nucleon {sup 36}Ar with {sup 197}Au, participant-spectator physics; consistency test of two measures of linear momentum transfer; the interaction of {approximately}30 MeV/nucleon projectiles with {sup 197}Au; gold target fragmentation by 800 GeV protons; target fragment mass distribution for the reaction of 13.3 GeV/nucleon {sup 28}Si with {sup 197}Au; momentum distributions of spallation products from the interaction of 400 MeV/nucleon {sup 12}C with {sup 197}Au; and pulse height defects for very low energy, very heavy ions.

  17. Oregon State University nuclear chemistry progress report, August 1, 1992--July 1, 1993

    SciTech Connect

    Loveland, W.

    1993-07-01

    This report discusses the following topics related to nuclear chemistry: Element 110; synthesis of heavy nuclei with complete fusion reactions involving radioactive nuclear beams; the interaction of 21--44 MeV/nucleon Xe with Au; MeV/nucleon {sup 86}Kr with {sup 197}Au; intermediate energy Ar-Th collisions; target-like fragments from the interaction of 29 MeV/nucleon {sup 208}Pb with {sup 197}Au; the intermediate of 22 and 32 MeV/nucleon {sup 16}O with {sup 197}Au; Au projectile fragmentation at 20 MeV/nucleon; relativistic heavy ion research; and pulse height defect measurements for very heavy ions.

  18. Nuclear chemistry progress report, September 1, 1982-August 31, 1983

    SciTech Connect

    Loveland, W.D.

    1983-09-01

    The following intermediate-energy (10 to 100 MeV/A) and relativistic (> 250 MeV/A) heavy-ion reactions were studied: Au target fragmentation; interaction of 35 MeV/nucleon /sup 12/C with /sup 197/Au and /sup 238/U, target fragment angular distributions in interaction of 86 MeV/nucleon /sup 12/C with /sup 197/Au, incomplete and complete fusion at intermediate energies (reaction of /sup 154/Sm with /sup 16/O and /sup 12/C), heavy target fragmentation, U target fragmentation at intermediate and high energies, rare earth (holmium) target fragmentation, target fragment angular distributions for 25.2 GeV /sup 12/C + /sup 197/Au, /sup 139/La + /sup 139/La reaction at 245 MeV/nucleon, target fragment kinematics in interaction of 1.8 GeV/nucleon /sup 40/Ar with /sup 197/Au and /sup 238/U, and a radiochemical search for anomalons. (DLC)

  19. Disassembly of hot nuclear matter formed in Au-induced reactions near the Fermi energy

    SciTech Connect

    Delis, D.N.

    1993-09-01

    Complex fragment emission has been studied in the 60 MeV/A {sup 197}Au + {sup 12}C, {sup 27}Al, {sup 51}V, {sup nat}Cu, and {sup 197}Au reactions. Velocity spectra, angular distributions and cross sections have been constructed for each target from the inclusive data. Coincidence data including 2-, 3-, 4-, and 5-fold events have also been examined. Furthermore neutron multiplicity distributions have been obtained for the above reactions by utilizing a novel neutron calorimetric approach.

  20. New data on cross-sections of deuteron induced nuclear reactions on gold up to 50 MeV and comparison of production routes of medically relevant Au and Hg radioisotopes

    NASA Astrophysics Data System (ADS)

    Tárkányi, F.; Hermanne, A.; Ditrói, F.; Takács, S.; Adam Rebeles, R.; Ignatyuk, A. V.

    2015-11-01

    Investigations of cross-sections of deuteron induced nuclear reactions on gold were extended up to 50 MeV by using the standard stacked foil irradiation technique and high resolution gamma-ray spectrometry. New cross-sections are reported for the 197Au(d,xn)197m,197g,195m,195g,193m,193gHg and 197Au(d,x)198m,198g,196m,196g,195,194Au nuclear reactions. The application for production of the medically relevant isotopes 198Au and 195m,195g,197m,197gHg is discussed, including the comparison with other charged particle induced production routes. The possible use of the 197Au(d,x)197m,197g,195m,193mHg and 196m,196gAu reactions for monitoring deuteron beam parameters is also investigated.

  1. Differential neutron-proton squeeze-out

    NASA Astrophysics Data System (ADS)

    Trautmann, W.; Chartier, M.; Leifels, Y.; Lemmon, R. C.; Li, Q.; Łukasik, J.; Pagano, A.; Pawłowski, P.; Russotto, P.; Wu, P.

    2009-04-01

    The elliptic flow (squeeze-out) of neutrons, protons and light complex particles in reactions of neutron-rich systems at relativistic energies is proposed as an observable, sensitive to the strength of the symmetry term in the equation of state at supra-normal densities. Preliminary results from a study of the existing FOPI/LAND data for 197Au + 197Au collisions at 400 A MeV with the UrQMD model favor a moderately soft symmetry term with a density dependence of the potential term proportional to ( with γ=0.6±0.3.

  2. Aligned breakup of heavy nuclear systems as a new type of deep inelastic collisions at small impact parameters

    SciTech Connect

    Wilczynski, J.; Swiderski, L.; Pagano, A.; Cardella, G.; De Filippo, E.; La Guidara, E.; Papa, M.; Pirrone, S.; Amorini, F.; Anzalone, A.; Cavallaro, S.; Colonna, M.; Di Toro, M.; Maiolino, C.; Porto, F.; Rizzo, F.; Russotto, P.; Auditore, L.

    2010-06-15

    An interesting process of violent reseparation of a heavy nuclear system into three or four fragments of comparable size was recently observed in {sup 197}Au+{sup 197}Au collisions at 15 MeV/nucleon. Combined analysis of the binary deep inelastic events and the ternary and quaternary breakup events demonstrates that the newly observed ternary and quaternary reactions belong to the same wide class of deep inelastic collisions as the conventional (binary) damped reactions. It is shown that the ternary and quaternary breakup reactions occur at extremely inelastic collisions corresponding to small impact parameters, while more peripheral collisions lead to well-known binary deep inelastic reactions.

  3. Formation of fragments in heavy-ion collisions using a modified clusterization method

    SciTech Connect

    Goyal, Supriya; Puri, Rajeev K.

    2011-04-15

    We study the formation and stability of the fragments by extending the minimum spanning tree method (MST) for clusterization. In this extension, each fragment is subjected to a binding-energy check calculated using the modified Bethe-Weizsaecker formula. Earlier, a constant binding-energy cut of 4 MeV/nucleon was imposed. Our results for {sup 197}Au+{sup 197}Au collisions are compared with ALADiN data and also with the calculations based on the simulated annealing technique. We shall show that the present modified version improves the agreement compared to the MST method.

  4. Neutron scattering studies in the actinide region. Progress report, August 1, 1992--July 31, 1993

    SciTech Connect

    Kegel, G.H.R.; Egan, J.J.

    1993-09-01

    This report discusses the following topics: Prompt fission neutron energy spectra for {sup 235}U and {sup 239}Pu; Two-parameter measurement of nuclear lifetimes; ``Black`` neutron detector; Data reduction techniques for neutron scattering experiments; Inelastic neutron scattering studies in {sup 197}Au; Elastic and inelastic scattering studies in {sup 239}Pu; and neutron induced defects in silicon dioxide MOS structures.

  5. IER-163 Post-Experiment MCNP Calculations (U)

    SciTech Connect

    Favorite, Jeffrey A.

    2012-06-04

    IER-163 has been modeled with high fidelity in MCNP6. The model k{sub eff} was high, as in other similar calculations. The fission ratio {sup 238}U(n,f)/{sup 235}U(n,f) was 12.6% too small compared with measurements; the ratio {sup 239}Pu(n,f)/{sup 235}U(n,f) was 11.5% too small compared with measurements; the iridium ratio {sup 193}Ir(n,n{prime})/{sup 191}Ir(n,{gamma}) was 16.4% too large; and the gold ratios {sup 197}Au(n,2n)/{sup 197}Au(n,{gamma}), {sup 197}Au(n,2n)/{sup 235}U(n,f), and {sup 197}Au(n,{gamma})/{sup 235}U(n,f) were within one standard deviation of the measured values. It is suggested that the calculated {sup 235}U fission rate is too large and the calculated {sup 238}U fission rate is too small.

  6. Nuclear Excitation by Electronic Transition - NEET

    SciTech Connect

    Becker, J.A.

    2002-06-10

    Experiments seeking to demonstrate nuclear excitation induced by synchrotron radiation have been enabled by the development of intense synchrotron radiation. The phenomena has been demonstrated in {sup 197}Au, while realistic upper limits for {sup 189}Os have been established. A new experiment in {sup 189}Os is described. The experimental claim of NEET in isomeric {sup 178}Hf is not credible.

  7. Production cross section of At radionuclides from 7Li+natPb and 9Be+natTl reactions

    NASA Astrophysics Data System (ADS)

    Maiti, Moumita; Lahiri, Susanta

    2011-12-01

    Earlier we reported theoretical studies on the probable production of astatine radionuclides from 6,7Li- and 9Be-induced reactions on natural lead and thallium targets, respectively. The production of astatine radionuclides were investigated experimentally with two heavy-ion-induced reactions: 9Be + natTl and 7Li + natPb. Formation cross sections of the evaporation residues, 207,208,209,210At, produced in the (HI,xn) channel, were measured by the stacked-foil technique followed by off-line γ spectrometry at low incident energies (<50 MeV). Measured excitation functions were interpreted in terms of a compound nuclear reaction mechanism using Weisskopf-Ewing and Hauser-Feshbach models. Measured cross-section values are lower than the respective theoretical predictions.

  8. The ASY-EOS experiment at GSI: investigating symmetry energy at supra-saturation densities

    NASA Astrophysics Data System (ADS)

    Russotto, P.; Chartier, M.; Cozma, M. D.; De Filippo, E.; Le Fèvre, A.; Gannon, S.; Gašparić, I.; Kiš, M.; Kupny, S.; Leifels, Y.; Lemmon, R. C.; Li, Q.; Łukasik, J.; Marini, P.; Pawłowski, P.; Santoro, S.; Trautmann, W.; Veselsky, M.; Acosta, L.; Adamczyk, M.; Al-Ajlan, A.; Al-Garawi, M.; Al-Homaidhi, S.; Amorini, F.; Auditore, L.; Aumann, T.; Ayyad, Y.; Baran, V.; Basrak, Z.; Bassini, R.; Benlliure, J.; Boiano, C.; Boisjoli, M.; Boretzky, K.; Brzychczyk, J.; Budzanowski, A.; Cardella, G.; Cammarata, P.; Chajecki, Z.; Chbihi, A.; Colonna, M.; Czech, B.; Di Toro, M.; Famiano, M.; Greco, V.; Grassi, L.; Guazzoni, C.; Guazzoni, P.; Heil, M.; Heilborn, L.; Introzzi, R.; Isobe, T.; Kezzar, K.; Krasznahorkay, A.; Kurz, N.; La Guidara, E.; Lanzalone, G.; Lasko, P.; Lombardo, I.; Lynch, W. G.; Matthews, Z.; May, L.; Minniti, T.; Mostazo, M.; Pagano, A.; Papa, M.; Pirrone, S.; Pleskac, R.; Politi, G.; Porto, F.; Reifarth, R.; Reisdorf, W.; Riccio, F.; Rizzo, F.; Rosato, E.; Rossi, D.; Simon, H.; Skwirczynska, I.; Sosin, Z.; Stuhl, L.; Trifirò, A.; Trimarchi, M.; Tsang, M. B.; Verde, G.; Vigilante, M.; Wieloch, A.; Wigg, P.; Wolter, H. H.; Wu, P.; Yennello, S.; Zambon, P.; Zetta, L.; Zoric, M.

    2014-03-01

    The elliptic-flow ratio of neutrons with respect to protons or light complex particles in reactions of heavy-ions at pre-relativistic energies has been proposed as an observable sensitive to the strength of the symmetry term of the nuclear equation of state at supra-saturation densities. The results obtained from the existing FOPI/LAND data for 197Au+197Au collisions at 400 MeV/nucleon in comparison with the UrQMD model simulations favoured a moderately soft symmetry term, but suffer from a considerable statistical uncertainty. These results have been confirmed by an independent analysis based on the Tübingen QMD simulations. In order to obtain an improved data set for Au+Au collisions and to extend the study to other systems, a new experiment was carried out at the GSI laboratory by the ASY-EOS collaboration. The present status of the data analysis is reported

  9. ASY-EOS experiment at GSI

    NASA Astrophysics Data System (ADS)

    Russotto, P.; Acosta, L.; Adamczyk, M.; Al-Ajlan, A.; Al-Garawi, M.; Al-Homaidhi, S.; Amorini, F.; Auditore, L.; Aumann, T.; Ayyad, Y.; Baran, V.; Basrak, Z.; Benlliure, J.; Boiano, C.; Boisjoli, C.; Boretzky, K.; Brzychczyk, J.; Budzanowski, A.; Cardella, G.; Cammarata, P.; Cavallaro, S.; Chajecki, Z.; Chartier, M.; Chbihi, A.; Colonna, M.; Czech, B.; De Filippo, E.; Di Toro, M.; Famiano, M.; Le Fevre, A.; Gašsparić, A.; Geraci, E.; Grassi, L.; Greco, V.; Guazzoni, C.; Guazzoni, P.; Heil, M.; Heilborn, L.; Introzzi, R.; Isobe, T.; Kezzar, K.; Kiš, M.; Kupny, S.; Kurz, N.; La Guidara, E.; Lanzalone, G.; Lasko, P.; Leifels, Y.; Lemmon, R.; Li, Q.; Lombardo, I.; Loria, D.; Lukasik, J.; Lynch, W. G.; Marini, P.; Matthews, Z.; May, L.; Minniti, T.; Mostazo, M.; Pagano, A.; Papa, M.; Pawlowski, P.; Petrovici, M.; Pirrone, S.; Politi, G.; Porto, F.; Reifarth, R.; Reisdorf, W.; Riccio, F.; Rizzo, F.; Rosato, E.; Rossi, D.; Santoro, S.; Simon, H.; Skwirczynska, I.; Sosin, Z.; Trautmann, W.; Trifirò, A.; Trimarchi, M.; Tsang, B.; Veselsky, M.; Verde, G.; Vigilante, M.; Wieloch, A.; Wigg, P.; Wilczynski, J.; Wolter, H. H.; Wu, P.; Yennello, S.; Zambon, P.; Zetta, L.; Zoric, M.

    2012-07-01

    The elliptic-flow ratio of neutrons with respect to protons in reactions of neutron rich Heavy-Ion at intermediate energies has been recently proposed as an observable sensitive to the strength of the symmetry term in the nuclear equation of state (EOS) at supra-saturation densities. The recent results obtained from the existing FOPI/LAND data for 197Au+197Au collisions at 400 MeV/nucleon in comparison with the UrQMD model allowed a first estimate of the symmetry term of the EOS but suffer from a considerable statistical uncertainty. In order to obtain an improved data set for Au+Au collisions and to extend the study to other systems, a new experiment was carried out at the GSI laboratory by the ASY-EOS collaboration in May 2011.

  10. The ASY-EOS experiment at GSI: investigating the symmetry energy at supra-saturation densities

    NASA Astrophysics Data System (ADS)

    Russotto, P.; Chartier, M.; De Filippo, E.; Le Fèvre, A.; Gannon, S.; Gašparić, I.; Kiš, M.; Kupny, S.; Leifels, Y.; Lemmon, R. C.; Łukasik, J.; Marini, P.; Pagano, A.; Pawłowski, P.; Santoro, S.; Trautmann, W.; Veselsky, M.; Acosta, L.; Adamczyk, M.; Al-Ajlan, A.; Al-Garawi, M.; Al-Homaidhi, S.; Amorini, F.; Auditore, L.; Aumann, T.; Ayyad, Y.; Baran, V.; Basrak, Z.; Benlliure, J.; Boiano, C.; Boisjoli, M.; Boretzky, K.; Brzychczyk, J.; Budzanowski, A.; Cardella, G.; Cammarata, P.; Chajecki, Z.; Chbihi, A.; Colonna, M.; Cozma, D.; Czech, B.; Di Toro, M.; Famiano, M.; Geraci, E.; Greco, V.; Grassi, L.; Guazzoni, C.; Guazzoni, P.; Heil, M.; Heilborn, L.; Introzzi, R.; Isobe, T.; Kezzar, K.; Krasznahorkay, A.; Kurz, N.; La Guidara, E.; Lanzalone, G.; Lasko, P.; Li, Q.; Lombardo, I.; Lynch, W. G.; Matthews, Z.; May, L.; Minniti, T.; Mostazo, M.; Papa, M.; Pirrone, S.; Politi, G.; Porto, F.; Reifarth, R.; Reisdorf, W.; Riccio, F.; Rizzo, F.; Rosato, E.; Rossi, D.; Simon, H.; Skwirczynska, I.; Sosin, Z.; Stuhl, L.; Trifirò, A.; Trimarchi, M.; Tsang, M. B.; Verde, G.; Vigilante, M.; Wieloch, A.; Wigg, P.; Wolter, H. H.; Wu, P.; Yennello, S.; Zambon, P.; Zetta, L.; Zoric, M.

    2013-03-01

    The elliptic-flow ratio of neutrons with respect to protons in reactions of neutron rich heavy-ions systems at intermediate energies has been proposed as an observable sensitive to the strength of the symmetry term in the nuclear Equation Of State (EOS) at supra-saturation densities. The recent results obtained from the existing FOPI/LAND data for 197Au+197Au collisions at 400 MeV/nucleon in comparison with the UrQMD model allowed a first estimate of the symmetry term of the EOS but suffer from a considerable statistical uncertainty. In order to obtain an improved data set for Au+Au collisions and to extend the study to other systems, a new experiment was carried out at the GSI laboratory by the ASY-EOS collaboration in May 2011.

  11. A measurement of the thermal neutron capture cross section of /sup 232/Th

    SciTech Connect

    Jones, R.T.; Merritt, J.S.; Okazaki, A.

    1986-06-01

    The thermal neutron capture cross section of /sup 232/Th has been measured relative to that of /sup 197/Au. Foils of gold, thorium metal, and thoria were irradiated together in the NRU reactor thermal column. The /sup 198/Au activity was assayed in a 4..pi gamma.. ionization chamber, which had been previously calibrated with samples of /sup 198/Au standardized by the 4..pi beta..-..gamma.. coincidence method. Protactinium-233 sources were also standardized by this method. Comparison of these sources with the irradiated thorium, by means of a Ge(Li) spectrometer, enabled the /sup 233/Pa activity in the thorium-bearing foils to be determined. Taking the 2200 m/s capture cross section of /sup 197/Au to be 98.8 b, that of /sup 232/Th is found to be 7.33+.0.06b. The uncertainty is at the 95% confidence level and includes an estimate of the systematic uncertainties.

  12. Photoactivation experiment on Au197 and its implications for the dipole strength in heavy nuclei

    NASA Astrophysics Data System (ADS)

    Nair, C.; Erhard, M.; Junghans, A. R.; Bemmerer, D.; Beyer, R.; Grosse, E.; Klug, J.; Kosev, K.; Rusev, G.; Schilling, K. D.; Schwengner, R.; Wagner, A.

    2008-11-01

    The 197Au(γ,n) reaction is used as an activation standard for photodisintegration studies on astrophysically relevant nuclei. At the bremsstrahlung facility of the superconducting electron accelerator ELBE (Electron Linear accelerator of high Brilliance and low Emittance) of Forschungszentrum Dresden-Rossendorf, photoactivation measurements on Au197 have been performed with bremsstrahlung endpoint energies from 8.0 to 15.5 MeV. The measured activation yield is compared with previous experiments as well as with calculations using Hauser-Feshbach statistical models. It is shown that the experimental data are best described by a two-Lorentzian parametrization with taking the axial deformation of Au197 into account. The experimental 197Au(γ,n) reaction yield measured at ELBE via the photoactivation method is found to be consistent with previous experimental data using photon scattering or neutron detection methods.

  13. Preparation of ion-track membranes of poly( p-phenylene terephthalamide): Control of pore shape by irradiation with different ion beams

    NASA Astrophysics Data System (ADS)

    Suzuki, Yasuyuki; Yamaki, Tetsuya; Koshikawa, Hiroshi; Asano, Masaharu; Voss, Kay-Obbe; Neumann, Reinhard; Yoshida, Masaru

    2007-07-01

    The preparation of ion-track membranes of thermally stable poly( p-phenylene terephthalamide) (PPTA) was performed by ion beam irradiation followed by chemical etching with a sodium hypochlorite solution. Cylindrical pores were observed in the membrane irradiated with 197Au and 238U ions at an energy of 11.1 MeV/n. In contrast, funnel shape pores appeared in the membrane irradiated with 84Kr, 102Ru and 129Xe ion at energies of 6.2, 3.6 and 3.5 MeV/n, respectively. The 197Au and 238U ion irradiation was found to exhibit more than four times larger sensitivity to the track etching under the same etching conditions. Consequently, the pore shape can be controlled by the masses and energies of the irradiated ions, in close relation to the etching sensitivity of the track.

  14. The ASY-EOS Experiment at GSI

    NASA Astrophysics Data System (ADS)

    Russotto, P.; Chartier, M.; Cozma, M. D.; De Filippo, E.; Le Fèvre, A.; Gannon, S.; Gašparić, I.; Kiš, M.; Kupny, S.; Leifels, Y.; Lemmon, R. C.; Li, Q.; Łukasik, J.; Marini, P.; Pawłowski, P.; Trautmann, W.; Acosta, L.; Adamczyk, M.; Al-Ajlan, A.; Al-Garawi, M.; Al-Homaidhi, S.; Amorini, F.; Auditore, L.; Aumann, T.; Ayyad, Y.; Baran, V.; Basrak, Z.; Bassini, R.; Benlliure, J.; Boiano, C.; Boisjoli, M.; Boretzky, K.; Brzychczyk, J.; Budzanowski, A.; Cardella, G.; Cammarata, P.; Chajecki, Z.; Chbihi, A.; Colonna, M.; Czech, B.; Di Toro, M.; Famiano, M.; Greco, V.; Grassi, L.; Guazzoni, C.; Guazzoni, P.; Heil, M.; Heilborn, L.; Introzzi, R.; Isobe, T.; Kezzar, K.; Krasznahorkay, A.; Kurz, N.; La Guidara, E.; Lanzalone, G.; Lasko, P.; Lombardo, I.; Lynch, W. G.; Matthews, Z.; May, L.; Minniti, T.; Mostazo, M.; Pagano, A.; Papa, M.; Pirrone, S.; Pleskac, R.; Politi, G.; Porto, F.; Reifarth, R.; Reisdorf, W.; Riccio, F.; Rizzo, F.; Rosato, E.; Rossi, D.; Santoro, S.; Simon, H.; Skwirczynska, I.; Sosin, Z.; Stuhl, L.; Trifirò, A.; Trimarchi, M.; Tsang, M. B.; Verde, G.; Veselsky, M.; Vigilante, M.; Wieloch, A.; Wigg, P.; Wolter, H. H.; Wu, P.; Yennello, S.; Zambon, P.; Zetta, L.; Zoric, M.

    2016-05-01

    The elliptic-flow ratio of neutrons with respect to protons or light complex particles in reactions of heavy ions at pre-relativistic energies has been proposed as an observable sensitive to the strength of the symmetry term of the nuclear equation of state at supra-saturation densities. In the ASY-EOS experiment at the GSI laboratory, flows of neutrons and light charged particles were measured for 197Au+197Au collisions at 400 MeV/nucleon. Flow results obtained for the Au+Au system, in comparison with predictions of the UrQMD transport model, confirm the moderately soft to linear density dependence of the symmetry energy deduced from the earlier FOPI-LAND data.

  15. Isospin effects via Coulomb forces on the onset of multifragmentation in light and heavily charged systems

    NASA Astrophysics Data System (ADS)

    Sharma, Arun; Bharti, Arun

    2016-03-01

    We concurrently study the isospin effects via Coulomb forces and the nuclear equation of state and its momentum dependence on the onset of multifragmentation, i.e., critical energy point, in the light and heavily charged reactions of 40Ar + 45Sc and 84Kr + 197Au , respectively, using the isospin-dependent quantum molecular dynamics model. We find that Coulomb forces influence the onset of multifragmentation and result in the shift of the critical energy point towards lower and higher incident energies with and without their presence, respectively. Also, we observe that the critical energy point is sharper for the heavily charged system of 84Kr + 197Au when compared with the light charged system of 40Ar + 45Sc , where a small dip is observed and thus leads to the dependence of onset of multifragmentation, i.e., the critical energy point, on the reaction asymmetry as well as on the Coulomb forces.

  16. Dynamical and statistical description of multifragmentation in heavy-ion collisions

    NASA Astrophysics Data System (ADS)

    Mao, Lihua; Wang, Ning; Ou, Li

    2015-04-01

    To explore the roles of the dynamical model and statistical model in the description of multifragmentation in heavy-ion collisions at intermediate energies, the fragments charge distributions of 197Au+197Au at 35 MeV/u are analyzed by using the hybrid model of improved quantum molecular dynamics (ImQMD) model plus the statistical model GEMINI. We find that, the ImQMD model can well describe the charge distributions of fragments produced in central and semicentral collisions. But for the peripheral collisions of Au+Au at 35 MeV/u, the statistical model is required at the end of the ImQMD simulations for the better description of the charge distribution of fragments. By using the hybrid model of ImQMD+GEMINI, the fragment charge distribution of Au+Au at 35 MeV/u can be reproduced reasonably well. The time evolution of the excitation energies of primary fragments is simultaneously investigated.

  17. Dynamics of strangeness production in heavy-ion collisions near threshold energies

    SciTech Connect

    Feng Zhaoqing; Jin Genming

    2010-11-15

    Within the framework of the improved isospin-dependent quantum molecular dynamics (ImIQMD) model, the dynamics of strangeness (K{sup 0,+}, {Lambda}, and {Sigma}{sup -,0,+}) production in heavy-ion collisions near threshold energies is investigated systematically, with the strange particles considered to be produced mainly by inelastic collisions of baryon-baryon and pion-baryon. Collisions in the region of suprasaturation densities of the dense baryonic matter formed in heavy-ion collisions dominate the yields of strangeness production. Total multiplicities as functions of incident energies and collision centralities are calculated with the Skyrme parameter SLy6. The excitation function of strangeness production is analyzed and also compared with the KaoS data for K{sup +} production in the reactions {sup 12}C+{sup 12}C and {sup 197}Au+{sup 197}Au.

  18. Nuclear chemistry progress report, September 1, 1984-August 31, 1985

    SciTech Connect

    Loveland, W.D.

    1985-09-01

    Progress is reported in these areas: fast and slow processes in the fragmentation of /sup 238/U by 85 A MeV /sup 12/C, Ho target fragmentation at intermediate energies, light fragment excitation functions, target fragment energy spectra in the interaction of 49 A and 85 A MeV /sup 12/C and /sup 197/Au, fragmentation of /sup 197/Au by 35 A MeV /sup 84/Kr, La target fragmentation by La and U ions, Ho target fragmentation induced by high energy /sup 12/C, /sup 20/Ne and /sup 40/Ar, and unusual projectile fragments formed in the interaction of 0.9 and 1.8 GeV /sup 40/Ar with Cu. (LEW)

  19. Nuclear Data Sheets for A = 230

    SciTech Connect

    Browne, E.; Tuli, J. K.

    2012-09-01

    The evaluators present in this publication spectroscopic data and level schemes from radioactive decay and nuclear reactions for all isobars with mass number A=230. This evaluation includes the first experimental evidence of 230Am, produced through the 197Au(40Ar,3n)234Bk (α decay to 230Am) reaction, E(40Ar)=188.4 MeV (2003MoZX).

  20. Azimuthal structures of produced particles in heavy-ion interactions

    SciTech Connect

    Vokal, S. Orlova, G. I.; Lehocka, S.

    2009-02-15

    The angular structures of particles produced in {sup 208}Pb at 158 A GeV/c and {sup 197}Au at 11.6 A GeV/c induced interactions with Ag(Br) nuclei in emulsion detector have been investigated. Nonstatistical well-ordered ring-like structures of produced particles in azimuthal plane of a collision have been found, and their parameters have been determined.

  1. Neutron capture cross section and capture gamma-ray spectra of 89Y

    NASA Astrophysics Data System (ADS)

    Katabuchi, Tatsuya; Okamiya, Tohomohiro; Yanagida, Shotaro; Mizumoto, Motoharu; Terada, Kazushi; Kimura, Atsushi; Iwamoto, Nobuyuki; Igashira, Masayuki

    2016-06-01

    The neutron capture cross section of 89Y was measured by the time-of-flight method in an energy range from 15 to 100 keV. A pulse-height weighting technique was applied to derive the capture yield. The absolute cross section was determined based on the standard reaciotn 197 Au(n, γ)198 Au reaction. The neutron capture γ-ray spectrum was derived by unfolding the pulse-height spectrum with detector response functions.

  2. Isotopic production cross sections in proton-nucleus collisions at 200 MeV

    SciTech Connect

    Machner, H.; Aschman, D.G.; Steyn, D.; Baruth-Ram, K.; Carter, J.; Sideras-Haddad, E.; Sellschop, J.P.F.; Cowley, A.A.; Goldenbaum, F.; Nangu, B.M.; Spoelstra, B.; Pilcher, J.V.; Smit, F.D.

    2006-04-15

    Intermediate-mass fragments from the interaction of {sup 27}Al, {sup 59}Co, and {sup 197}Au with 200-MeV protons were measured in an angular range from 20 deg. to 120 deg. in the laboratory system. The fragments, ranging from isotopes of helium up to isotopes of carbon, were isotopically resolved. Double-differential cross sections, energy-differential cross sections, and total cross sections were extracted.

  3. Discovery of Highly Excited Long-Lived Isomers in Neutron-Rich Hafnium and Tantalum Isotopes through Direct Mass Measurements

    SciTech Connect

    Reed, M. W.; Cullen, I. J.; Walker, P. M.; Deo, A. Y.; Kempley, R. S.; Swan, T. P. D.; Litvinov, Yu. A.; Winckler, N.; Blaum, K.; Bosch, F.; Dimopoulou, C.; Farinon, F.; Heil, M.; Knoebel, R.; Kozhuharov, C.; Kurcewicz, J.; Kuzminchuk, N.; Litvinov, S.; Nociforo, C.; Nolden, F.

    2010-10-22

    A study of cooled {sup 197}Au projectile-fragmentation products has been performed with a storage ring. This has enabled metastable nuclear excitations with energies up to 3 MeV, and half-lives extending to minutes or longer, to be identified in the neutron-rich nuclides {sup 183,184,186}Hf and {sup 186,187}Ta. The results support the prediction of a strongly favored isomer region near neutron number 116.

  4. Use Of The BigSol Time Of Flight Spectrometer In The Study Of Superheavy Element Production

    SciTech Connect

    Barbui, M.; Hagel, K.; Natowitz, J. B.; Wada, R.; Sahu, P. K.; Materna, T.; Chen, Z.; Quin, L.; Chubaryan, G.; Souliotis, G. A.; Bonasera, A.; Fabris, D.; Lunardon, M.; Morando, M.; Moretto, S.; Nebbia, G.; Pesente, S.; Viesti, G.; Bocci, F.; Cinausero, M.

    2011-06-01

    A time-of-flight spectrometer with the BigSol superconducting solenoid at Texas A and M was used to investigate the possibility to produce heavy and superheavy nuclei by using two body collisions involving heavy projectiles and targets. The reaction {sup 197}Au+{sup 232}Th at 7.5 AMeV is studied in this work. Preliminary results for the yields of heavy nuclei are presented.

  5. Fission fragment mass distributions in reactions forming the {sup 213}Fr compound nucleus

    SciTech Connect

    Appannababu, S.; Mukherjee, S.; Deshmukh, N. N.; Rath, P. K.; Singh, N. L.; Nayak, B. K.; Thomas, R. G.; Choudhury, R. K.; Sugathan, P.; Jhingan, A.; Negi, D.; Prasad, E.

    2011-03-15

    The fission fragment mass angle correlations and mass ratio distributions have been investigated for the two systems {sup 16}O+{sup 197}Au and {sup 27}Al+{sup 186}W, leading to the same compound nucleus {sup 213}Fr around the Coulomb barrier energies. Systematic analysis of the variance of the mass distributions as a function of temperature and angular momentum suggests true compound nuclear fission for both the reactions, indicating the absence of nonequilibrium fission processes.

  6. Nuclear physics experiments for the astrophysical p process

    NASA Astrophysics Data System (ADS)

    Sauerwein, A.; Elvers, M.; Endres, J.; Hasper, J.; Hennig, A.; Netterdon, L.; Zilges, A.

    2011-04-01

    We studied the two astrophysically interesting reactions 141PrPm and 92MoTc with the activation method and with the in-beam method, respectively. The 141PrPm experiment was performed at the cyclotron of the ‘Physikalisch Technische Bundesanstalt (PTB)’ in Braunschweig, Germany, and the reaction was studied within and just above the so-called Gamow window. In this proceedings, we present the experimental details of this measurement. The proton-capture reaction on the neutron-magic nucleus 92Mo was studied at energies relevant for the astrophysical p process. The reaction was investigated by the in-beam technique using the γ-ray detector array HORUS (High efficient Observatory for γ-Ray Unique Spectroscopy) at the TANDEM ion accelerator at the University of Cologne. The preliminary experimental results are compared to data stemming from other measurements.

  7. Multifragment Emission in Central Collisions of ARGON-36 + GOLD-197 at E/a = 50, 80 and 110 Mev

    NASA Astrophysics Data System (ADS)

    Phair, Larry William

    Multifragment disintegrations of highly excited nuclear systems may carry information about the equation of state and the liquid-gas phase transition of low density nuclear matter. The mechanism causing multifragment decays is, however, not yet understood. To study this phenomenon we constructed a low threshold 4pi charged-particle detector, the Miniball, and studied the reaction of ^{36}Ar + ^{197}Au at E/A=50, 80 and 110 MeV. For central collisions, the chance for equilibration of the system is highest. We therefore determined the most efficient method of selecting central collisions by comparing the ability of several global observables to select events with suppressed projectile-like fragment emission and small anisotropic azimuthal emission patterns. Similar event selection was obtained by using the following global observables: the charged particle multiplicity N _{c}, the total transverse energy E_{t}, and summed charge emitted at midrapidity Z_{y}. An average multiplicity of 4 intermediate mass fragments (IMF) was observed for the most central collisions at E/A = 110 MeV. These IMF multiplicities are consistent with predictions from a statistical model for evaporation from an expanding compound nucleus. The statistical decay model predictions are sensitive to the low-density nuclear equation of state. The IMF yields are also consistent with predictions from a standard percolation model for the ^ {36}Ar + ^{197} Au system. Assuming a spherical decay geometry, percolation fails, however, to predict the measured fragment multiplicities for the heavier system ^ {129}Xe + ^{197} Au at E/A = 50 MeV investigated by our group. For noncompact decay configurations (bubbles and toroids) the percolation model can reproduce the large fragment multiplicities observed for this reaction.

  8. HETC96/MORSE calculations of activations in KEK beam stop and room by 500-MeV protons and comparisons with experiments

    SciTech Connect

    Fu, C.Y.; Gabriel, T.A.

    1997-05-01

    The 1996 version of HETC has a pre-equilibrium reaction model to bridge the gap between the existing intranuclear-cascade and evaporation models. This code was used to calculate proton-induced activations, to calculate neutron fluxes for neutron energies above 19.6 MeV, and to write the neutron source for lower energies to be transported further by MORSE. For MORSE, the HILO cross section library was used for neutron transport for all detectors. Additionally for the {sup 197}Au(n, {gamma}) detector, the BUGLE96 library was used to study the effects of the low-lying {sup 57}Fe inelastic levels and the resonance self-shielding in iron. Neutron fluxes were obtained from the track-length estimator for detectors inside the beam stop and from the boundary-crossing estimator for detectors attached to the surfaces of the concrete walls. Activation cross sections given in JAERI-Data/Code are combined with the calculated neutron fluxes to get the saturated activities induced by neutrons. C/E values are too low (0.5) for Fe(N, {chi}){sup 54}Mn, close to unity for Cu(n, {chi}){sup 58}Co, and too high (6.0) for {sup 197}Au (n, {gamma}){sup 198}Au. It is difficult to interpret the disagreements because most of the activation cross sections are also calculated and their uncertainties are not known. However, the calculated results are in good agreement with those calculated by others using different codes. Calculated results for four of the ten activations reported here have not been done previously, and among the four, {sup 197}Au(n, {gamma}) is the most bothersome because its cross section is the most well known while the calculated activations for most detector locations are in largest disagreement with experiments.

  9. Nuclear chemistry progress report, Oregon State University. August 1, 1995--August 1, 1996

    SciTech Connect

    Loveland, W.

    1996-12-31

    In this report, the authors summarize the highlights of the work done between August 1, 1995, and August 1, 1996. The work reported herein is the result of a collaborative effort between the nuclear chemists at Oregon State University and many other individuals and research groups. Each project discussed was the result of a joint effort of the groups, interchanging roles in data acquisition and analysis. The work described is part of a project involving the study of low energy (< 10 MeV/nucleon), and intermediate energy (10--100 MeV/nucleon) heavy ion reactions. Their work in the low energy regime included: the first US studies of fusion utilizing radioactive beams. Half of their effort was spent in the study of intermediate energy nuclear collisions. Among the accomplishments were: the establishment of a systematics of angular momentum transfer in peripheral collisions; completion of the first portion of high resolution studies of heavy residue formation in reactions induced by 20 MeV/nucleon {sup 197}Au utilizing the MSU A1200 separator; synthesis of several new neutron-deficient nuclides in reactions of 20 MeV/nucleon {sup 197}Au with heavy targets (Ti, Zr and Au); their participation in exclusive studies of heavy residue formation in the reaction of 35 MeV/nucleon {sup 86}Kr with {sup 197}Au in which it was found that the residues had large associated particle multiplicities indicating their formation in highly dissipative collisions, and that particle emission leading to residue formation relative to fission was favored as the dissipated energy increased.

  10. A New Signal Processing Technique for Neutron Capture Cross Section Measurement Based on Pulse Width Analysis

    NASA Astrophysics Data System (ADS)

    Katabuchi, T.; Matsuhashi, T.; Terada, K.; Mizumoto, M.; Hirose, K.; Kimura, A.; Furutaka, K.; Hara, K. Y.; Harada, H.; Hori, J.; Igashira, M.; Kamiyama, T.; Kitatani, F.; Kino, K.; Kiyanagi, Y.; Koizumi, M.; Nakamura, S.; Oshima, M.; Toh, Y.

    2014-05-01

    A fast data acquisition method based on pulse width analysis was developed for γ-ray spectroscopy with an NaI(Tl) detector. The new method was tested in experiments with standard γ-ray sources and pulsed neutron beam from a spallation neutron source. Pulse height spectra were successfully reconstructed from pulse width distribution by use of an energy calibration curve. The 197Au(n, γ)198Au cross section was measured by this method to test the viability. The obtained experimental cross section showed a good agreement with a calculation using the resonance parameters of JENDL-4.0.

  11. The Multi-Purpose Detector (MPD) of the collider experiment

    NASA Astrophysics Data System (ADS)

    Golovatyuk, V.; Kekelidze, V.; Kolesnikov, V.; Rogachevsky, O.; Sorin, A.

    2016-08-01

    The project NICA (Nuclotron-based Ion Collider fAcility) is aimed to study dense baryonic matter in heavy-ion collisions in the energy range up to √{s_{NN}} = 11 GeV with average luminosity of L = 1027 cm-2s-1 (for 197Au79). The experimental program at the NICA collider will be performed with the Multi-Purpose Detector (MPD). We report on the main physics objectives of the NICA heavy-ion program and present the main detector components.

  12. Measurement of the space-time extent of the hard-photon emitting source in heavy-ion collisions at 100 MeV/nucleon

    SciTech Connect

    Badala, A.; Barbera, R.; Palmeri, A.; Pappalardo, G.S.; Riggi, F.; Russo, A.C.; Turrisi, R.; Barbera, R.; Riggi, F.; Rizza, G.; Russo, G.; Turrisi, R.; Russo, G.

    1997-05-01

    The correlation between the couples of high-energy photons (E{sub {gamma}}{gt}30MeV) detected in the reactions induced by a {sup 36}Ar beam on {sup 27}Al, {sup 112}Sn, and {sup 197}Au targets at 95 MeV/nucleon has been analyzed with the intensity interferometry technique. Both the size and lifetime of the emitting source have been quantitatively evaluated. Results support the nucleon-nucleon picture as the dominant hard-photon production mechanism. {copyright} {ital 1997} {ital The American Physical Society}

  13. The Isospin Diffusion in 58Ni-INDUCED Reactions at Intermediate Energies

    NASA Astrophysics Data System (ADS)

    Galichet, E.; Rivet, M. F.; Borderie, B.; Colonna, M.; Bougault, R.; Durand, D.; Le Neindre, N.; Lopez, O.; Manduci, L.; Vient, E.; Chbihi, A.; Frankland, J. D.; Wieleczko, J. P.; Dayras, R.; Volant, C.; Guinet, D. C. R.; Lautesse, P.; Parlog, M.; Rosato, E.; Vigilante, M.

    Isospin diffusion is probed as a function of the dissipated energy by studying two systems 58Ni+58Ni and 58Ni+197Au, over the incident energy range 52-74A MeV. Experimental data are compared with the results of a microscopic transport model with two different parameterizations of the symmetry energy term. A better overall agreement between data and simulations is obtained when using a symmetry term with a potential part linearly increasing with nuclear density. The isospin equilibration time at 52 A MeV is estimated to 130 ± 10 fm/c.

  14. Effects of the magnetic field on the spallation reaction implemented by BUU coupled with a phase-space coalescence afterburner

    NASA Astrophysics Data System (ADS)

    Liu, Yang; Yong, Gao-Chan; Zuo, Wei

    2012-08-01

    Based on the Boltzmann-Uehling-Uhlenbeck (BUU) transport model coupled with a phase-space coalescence afterburner, the spallation reaction p + 197Au at the incident beam energy Ebeam = 800 MeV/nucleon is studied. We find that the number of test particles per nucleon has minor effects on the neutron-to-proton ratio (n/p) of the produced heavier fragments while it affects much their yields. The external strong magnetic field affects the production of heavier fragments more than the n/p of produced fragments. The n/p of free nucleons is greatly affected by the strong magnetic field, especially for the nucleons with lower energies.

  15. Neutron capture cross sections of natural Yb, /sup 170/Yb, /sup 175/Lu, and /sup 184/W in the energy range from 5 to 200 keV for the /sup 176/Lu-chronometer

    SciTech Connect

    Beer, H.; Wisshak, K.; Kaeppeler, F.

    1980-09-01

    The neutron capture cross sections of natural Yb, /sup 170/Yb, /sup 175/Lu and /sup 184/W have been measured in the keV neutron energy range with a pulsed Van de Graaff accelerator using the kinematically collimated neutron beam from the /sup 7/Li(p,n) and the T(p,n) reaction. Prompt capture gamma rays were registered by a Moxon-Rae detector. All measurements were performed in a single run relative to the /sup 197/Au cross section as a standard. The cross sections of /sup 175/Lu and /sup 170/Yb were used to investigate the /sup 176/Lu-cosmic clock.

  16. Modern Rutherford experiment: tunneling of the most neutron-rich nucleus.

    PubMed

    Lemasson, A; Shrivastava, A; Navin, A; Rejmund, M; Keeley, N; Zelevinsky, V; Bhattacharyya, S; Chatterjee, A; de France, G; Jacquot, B; Nanal, V; Pillay, R G; Raabe, R; Schmitt, C

    2009-12-01

    A modern variation of the Rutherford experiment to probe the tunneling of exotic nuclear matter from the measurement of the residues formed in the bombardment of (197)Au by extremely neutron-rich (8)He nuclei is presented. Using a novel off-beam technique the most precise and accurate measurements of fusion and neutron transfer involving reaccelerated unstable beams are reported. The results show unusual behavior of the tunneling of (8)He compared to that for lighter helium isotopes, highlighting the role of the intrinsic structure of composite many-body quantum systems and pairing correlations. PMID:20366144

  17. Modern Rutherford Experiment: Tunneling of the Most Neutron-Rich Nucleus

    SciTech Connect

    Lemasson, A.; Navin, A.; Rejmund, M.; France, G. de; Jacquot, B.; Raabe, R.; Schmitt, C.; Keeley, N.; Zelevinsky, V.; Bhattacharyya, S.; Nanal, V.; Pillay, R. G.

    2009-12-04

    A modern variation of the Rutherford experiment to probe the tunneling of exotic nuclear matter from the measurement of the residues formed in the bombardment of {sup 197}Au by extremely neutron-rich {sup 8}He nuclei is presented. Using a novel off-beam technique the most precise and accurate measurements of fusion and neutron transfer involving reaccelerated unstable beams are reported. The results show unusual behavior of the tunneling of {sup 8}He compared to that for lighter helium isotopes, highlighting the role of the intrinsic structure of composite many-body quantum systems and pairing correlations.

  18. Neutron capture cross section standards for BNL 325, Fourth Edition

    SciTech Connect

    Holden, N.E.

    1981-01-01

    This report evaluates the experimental data and recommends values for the thermal neutron cross sections and resonance integrals for the neutron capture reactions: /sup 55/Mn(n,..gamma..), /sup 59/Co(n,..gamma..) and /sup 197/Au(n,..gamma..). The failure of lithium and boron as standards due to the natural variation of the absorption cross sections of these elements is discussed. The Westcott convention, which describes the neutron spectrum as a thermal Maxwellian distribution with an epithermal component, is also discussed.

  19. Calculation of proton total reaction cross sections for some target nuclei in incident energy range of 10-600 MeV

    SciTech Connect

    Bueyuekuslu, H.; Kaplan, A.; Aydin, A.; Tel, E.; Yildirim, G.

    2010-10-15

    In this study, proton total reaction cross sections have been investigated for some isotopes such as {sup 12}C, {sup 27}Al, {sup 9}Be, {sup 16}O, {sup 181}Ta, {sup 197}Au, {sup 6}Li, and {sup 14}N by a proton beam up to 600 MeV. Calculation of the proton total cross sections has been carried out by the analytic expression formulated by M.A. Alvi by using Coulomb-modified Glauber theory with the Helm model nuclear form factor. The obtained results have been discussed and compared with the available experimental data and found to be in agreement with each other.

  20. Counting the number of correlated pairs in a nucleus

    SciTech Connect

    Vanhalst, Maarten; Cosyn, Wim; Ryckebusch, Jan

    2011-09-15

    We suggest that the number of correlated nucleon pairs in an arbitrary nucleus can be estimated by counting the number of proton-neutron, proton-proton, and neutron-neutron pairs residing in a relative S state. We present numerical calculations of those amounts for the nuclei {sup 4}He, {sup 9}Be, {sup 12}C, {sup 27}Al, {sup 40}Ca, {sup 48}Ca, {sup 56}Fe, {sup 63}Cu, {sup 108}Ag, and {sup 197}Au. The results are used to predict the values of the ratios of the per-nucleon electron-nucleus inelastic scattering cross section to the deuteron in the kinematic regime where correlations dominate.

  1. Effects of collectivity on target-fragmentation reactions

    SciTech Connect

    Cumming, J.B.

    1980-01-07

    A new approach based on the collective tube model is developed for understanding momentum transfer to target fragments in high-energy hadron-nucleus collisions. Collectivity manifests itself in an enhanced dependence of momentum transfer on projectile energy, consistent with experimental results for deep-spallation reactions. The effective target for /sup 149/Tb production from /sup 197/Au by high-energy protons is deduced to consist of 3.1 +- 0.4 nucleons. Extensions of this model to nucleus-nucleus collisions are discussed.

  2. Quantum description of coupling to neutron-rearrangement channels in fusion reactions near the Coulomb barrier

    SciTech Connect

    Samarin, V. V.

    2015-10-15

    The fusion cross sections for the {sup 17,18}O+{sup 27}Al, {sup 18}O+{sup 58}Ni, and {sup 6}He+{sup 197}Au reactions were calculated by the coupled-channel method. The radial dependence of matrices that describe coupling to valence-neutron-rearrangement channels was determined with the aid of two-center wave functions. The coupling-strength parameters were evaluated on the basis of numerically solving the time-dependent Schrödinger equation. Satisfactory agreement with experimental data was obtained.

  3. Fusion and neutron transfer reactions with weakly bound nuclei within time-dependent and coupled channel approaches

    NASA Astrophysics Data System (ADS)

    Samarin, V. V.

    2016-05-01

    The time-dependent Schrödinger equation and the coupled channel approach based on the method of perturbed stationary two-center states are used to describe nucleon transfers and fusion in low-energy nuclear reactions. Results of the cross sections calculation for the formation of the 198Au and fusion in the 6He+197Au reaction and for the formation of the 65Zn in 6He+64Zn reaction agree satisfactorily with the experimental data near the barrier. The Feynman's continual integrals calculations for a few-body systems were used for the proposal of the new form of the shell model mean field for helium isotopes.

  4. Dynamical coupling of pygmy and giant resonances in relativistic Coulomb excitation

    NASA Astrophysics Data System (ADS)

    Brady, N. S.; Aumann, T.; Bertulani, C. A.; Thomas, J. O.

    2016-06-01

    We study the Coulomb excitation of pygmy dipole resonances (PDR) in heavy ion reactions at 100 MeV/nucleon and above. The reactions 68Ni +197Au and 68Ni +208Pb are taken as practical examples. Our goal is to address the question of the influence of giant resonances on the PDR as the dynamics of the collision evolves. We show that the coupling to the giant resonances affects considerably the excitation probabilities of the PDR, a result that indicates the need of an improved theoretical treatment of the reaction dynamics at these bombarding energies.

  5. The liquid to vapor phase transition in excited nuclei

    SciTech Connect

    Elliott, J.B.; Moretto, L.G.; Phair, L.; Wozniak, G.J.; Beaulieu, L.; Breuer, H.; Korteling, R.G.; Kwiatkowski, K.; Lefort, T.; Pienkowski, L.; Ruangma, A.; Viola, V.E.; Yennello, S.J.

    2001-05-08

    For many years it has been speculated that excited nuclei would undergo a liquid to vapor phase transition. For even longer, it has been known that clusterization in a vapor carries direct information on the liquid-vapor equilibrium according to Fisher's droplet model. Now the thermal component of the 8 GeV/c pion + 197 Au multifragmentation data of the ISiS Collaboration is shown to follow the scaling predicted by Fisher's model, thus providing the strongest evidence yet of the liquid to vapor phase transition.

  6. Decay Properties of New Isotopes 234Bk and 230Am, and Even-Even Nuclides 234Cm and 230Pu

    NASA Astrophysics Data System (ADS)

    Kaji, Daiya; Morimoto, Kouji; Haba, Hiromitsu; Ideguchi, Eiji; Koura, Hiroyuki; Morita, Kosuke

    2016-01-01

    A neutron-deficient berkelium isotope of 234Bk produced via 197Au(40Ar,3n) reaction and the daughter product of 230Am were newly identified. Alpha-decay energies of eleven 234Bk were found at 7.62-7.96 MeV, and six fission events that correlated with the α-decay of 234Bk were observed. The half-lives of 234Bk and 230Am were determined to be 19 - 4 + 6 s and 32 - 9 + 22 s, respectively. The 234Cm followed by the β-decay of 234Bk was also identified.

  7. Isospin diffusion in {sup 58}Ni-induced reactions at intermediate energies. I. Experimental results

    SciTech Connect

    Galichet, E.; Rivet, M. F.; Borderie, B.; Bougault, R.; Durand, D.; Lopez, O.; Manduci, L.; Tamain, B.; Vient, E.; Dayras, R.; Volant, C.; Rosato, E.

    2009-06-15

    Isospin diffusion in semiperipheral collisions is probed as a function of the dissipated energy by studying two systems {sup 58}Ni+{sup 58}Ni and {sup 58}Ni+{sup 197}Au, over the incident energy range 52A-74A MeV. A close examination of the multiplicities of light products in the forward part of the phase space clearly shows an influence of the isospin of the target on the neutron richness of these products. A progressive isospin diffusion is observed when collisions become more central, in connection with the interaction time.

  8. Hard photons and neutral pions as probes of hot and dense nuclear matter

    NASA Astrophysics Data System (ADS)

    Schutz, Y.; Martínez, G.; Marqués, F. M.; Marín, A.; Matulewicz, T.; Ostendorf, R. W.; Bożek, P.; Delagrange, H.; Díaz, J.; Franke, M.; Gudima, K. K.; Hlaváč, S.; Holzmann, R.; Lautridou, P.; Lefèvre, F.; Löhner, H.; Mittig, W.; Płoszajczak, M.; van Pol, J. H. G.; Québert, J.; Roussel-Chomaz, P.; Schubert, A.; Siemssen, R. H.; Simon, R. S.; Sujkowski, Z.; Toneev, V. D.; Wagner, V.; Wilschut, H. W.; Wolf, Gy.

    1997-02-01

    The dynamics of heavy-ion collisions is studied in an energy domain in the vicinity of the Fermi energy. The early history of the collision is analyzed from the theoretical and experimental point of view in which the message conveyed by bremsstrahlung photons and neutral pions is exploited. The Boltzmann-Uehling-Uhlenbeck model and the Dubna Cascade Model, both based on similar principles but each adopting different computation technics, are briefly described and their respective predictions are discussed. In particular the emission pattern of bremsstrahlung photons is discussed. The photon production has been measured in the systems 86Kr+ 58Ni at 60 A MeV, 181Ta+ 197Au at 40 A MeV and 208Pb+ 197Au at 30 A MeV and energy spectra, angular distributions and two-photon correlations have been analyzed. We find that bremsstrahlung photons are emitted from two distinct sources that can be correlated with nuclear-matter density oscillations. The properties of photon emission are discussed in terms of collective properties of nuclear matter. The high energy tail of the photon spectrum is interpreted by π0 and Δ decay but predominantly by radiative capture of pions. The π0 absorption in the nuclear medium is further analyzed by examining their emission pattern.

  9. Neutron-capture cross-section measurements of 74Ge and 76Ge in the energy region 0.4-14.8 MeV for neutrinoless double β decay applications

    NASA Astrophysics Data System (ADS)

    Bhike, Megha; Tornow, Werner

    2013-10-01

    Fast neutron capture cross sections for the reactions 74Ge(n, γ)75Ge and 76Ge(n, γ)77Ge have been measured in the neutron energy region 0.4-14.8 MeV with the activation method. The results are important to identify backgrounds in the neutrinoless double- β decay experiments GERDA and MAJORANA, which use germanium as both source and detector. Isotopically enriched targets which consisted of 86% of 76Ge and 14% of 74Ge were irradiated with mono-energetic neutrons produced via 3H(p,n)3He, 2H(d,n)3He and 3H(d,n)4He reactions. The cross sections were determined relative to 197Au(n, γ)198Au, 115In(n,n')115mIn and 197Au(n,2n)196Au standard cross sections. The activities of the products were measured using high-resolution γ-ray spctroscopy. The present results are compared with the evaluated data from ENDF/B-VII.1 and TALYS.

  10. Effect of Δ potential on the π-/π+ ratio in heavy-ion collisions at intermediate energies

    NASA Astrophysics Data System (ADS)

    Guo, Wen-Mei; Yong, Gao-Chan; Zuo, Wei

    2015-11-01

    Based on the isospin-dependent Boltzmann-Uehling-Uhlenbeck (IBUU) transport model, effects of the Δ resonance potential on the free n /p and π-/π+ ratios in the central collision of 197Au+197Au at beam energies of 200 and 400 MeV/nucleon are studied. It is found that the effect of the Δ potential on the ratio of pre-equilibrium free n /p is invisible. The effect of Δ isovector potential on the kinetic-energy-integrating ratio of π-/π+ may be observable only at lower incident beam energies and with stiffer symmetry energy. The strength of the Δ isoscalar potential affects the height of the π-/π+ ratio around the Coulomb peak but does not affect the kinetic-energy-integrating ratio π-/π+ . In heavy-ion collisions at intermediate energies, relating to the question of nonconservation of energy on Δ or π productions, one can replace the Δ potential by the nucleon isoscalar potential especially when a soft symmetry energy is employed.

  11. The Symmetry Energy in Nuclear Reactions

    NASA Astrophysics Data System (ADS)

    Trautmann, W.; Bianchin, S.; Botvina, A. S.; Le Fèvre, A.; Leifels, Y.; Sfienti, C.; Buyukcizmeci, N.; Ogul, R.; Mishustin, I. N.; Chartier, M.; Wu, P. Z.; Lemmon, R. C.; Li, Q.; Łukasik, J.; Pawłowski, P.; Pagano, A.; Russotto, P.; ALADIN Collaboration

    New results for the strength of the symmetry energy are presented which illustrate the complementary aspects encountered in reactions probing nuclear densities below and above saturation. A systematic study of isotopic effects in spectator fragmentation was performed at the ALADIN spectrometer with 124Sn primary and 107Sn and 124La secondary beams of 600 MeV/nucleon incident energy. The analysis within the Statistical Fragmentation Model shows that the symmetry-term coefficient entering the liquid-drop description of the emerging fragments decreases significantly as the multiplicity of fragments and light particles from the disintegration of the produced spectator systems increases. Higher densities were probed in the FOPI/LAND study of nucleon and light-particle flows in central and mid-peripheral collisions of 197Au+197Au nuclei at 400 MeV/nucleon incident energy. From the comparison of the measured neutron and hydrogen squeeze-out ratios with predictions of the UrQMD model a moderately soft symmetry term with a density dependence of the potential term proportional to (ρ/ρ0)γ with γ = 0.9 ± 0.3 is favored.

  12. Toward a model-independent constraint of the high-density dependence of the symmetry energy

    NASA Astrophysics Data System (ADS)

    Cozma, M. D.; Leifels, Y.; Trautmann, W.; Li, Q.; Russotto, P.

    2013-10-01

    Neutron-proton elliptic flow difference and ratio have been shown to be promising observables in the attempt to constrain the density dependence of the symmetry energy above the saturation point from heavy-ion collision data. Their dependence on model parameters such as microscopic nucleon-nucleon cross sections, compressibility of nuclear matter, optical potential, and symmetry energy parametrization is thoroughly studied. By using a parametrization of the symmetry energy derived from the momentum-dependent Gogny force in conjunction with the Tübingen quantum molecular dynamics (QMD) model and comparing the results with the experimental FOPI-LAND data for 197Au +197Au collisions at 400 MeV/nucleon, a moderately stiff (Lsym=122±57 MeV and Ksym=229±363 MeV) symmetry energy is extracted, a result that agrees with that of a similar study that employed the UrQMD transport model and a power-law parametrization of the symmetry energy. This contrasts with diverging results extracted from the FOPI π-/π+ ratio available in the literature.

  13. The symmetry energy in nuclear reactions

    NASA Astrophysics Data System (ADS)

    Trautmann, W.

    2010-03-01

    The complementary aspects of the strength of the symmetry energy at nuclear densities below and above saturation are illustrated with recent results from experiments performed at the GSI laboratory with relativistic heavy-ion beams. A systematic study of isotopic effects in spectator fragmentation was performed at the ALADIN spectrometer with 124Sn primary and 107Sn and 124La secondary beams of 600 MeV/nucleon incident energy. The analysis within the Statistical Fragmentation Model reveals that the symmetry-term coefficient entering the liquid-drop description of the emerging fragments decreases significantly as the disintegration of the spectator system into fragments and light particles increases. Higher densities were probed in more central collisions of 197Au + 197Au nuclei at 400 MeV/nucleon. The results obtained from the analysis of the FOPI/LAND experimental data on neutron and hydrogen squeeze-out in comparison with UrQMD model predictions favor a moderately soft symmetry term with a density dependence of the potential term proportional to (ρ with γ=0.9±0.3.

  14. Photon and neutral pion production in Au+Au collisions at {radical}s{sub NN} = 130 GeV

    SciTech Connect

    Adams, J.; Adler, C.; Aggarwal, M.M.; Ahammed, Z.; Amonett, J.; Anderson, B.D.; Anderson, M.; Arkhipkin, D.; Averichev, G.S.; Badyal, S.K.; Balewski, J.; Barannikova, O.; Barnby, L.S.; Baudot, J.; Bekele, S.; Belaga, V.V.; Bellwied, R.; Berger, J.; Bezverkhny, B.I.; Bhardwaj, S.; Bhaskar, P.; Bhati, A.K.; Bichsel, H.; Billmeier, A.; Bland, L.C.; Blyth, C.O.; Bonner, B. E.; Botje, M.; Boucham, A.; Brandin, A.; Bravar, A.; Cadman, R.V.; Cai, X.Z.; Caines, H.; Calderon de la Barca Sanchez, M.; Carroll, J.; Castillo, J.; Castro, M.; Cebra, D.; Chaloupka, P.; Chattopadhyay, S.; Chen, H.F.; Chen, Y.; Chernenko, S.P.; Cherney, M.; Chikanian, A.; Choi, B.; Christie, W.; Coffin, J.P.; Cormier, T.M.; Cramer, J.G.; Crawford, H.J.; Das, D.; Das, S.; Derevschikov, A.A.; Didenko, L.; Dietel, T.; Dong, X.; Draper, J.E.; Du, F.; Dubey, A.K.; Dunin, V.B.; Dunlop, J.C.; Dutta Majumdar, M.R.; Eckardt, V.; Efimov, L.G.; Emelianov, V.; Engelage, J.; Eppley, G.; Erazmus, B.; Estienne, M.; Fachini, P.; Faine, V.; Faivre, J.; Fatemi, R.; Filimonov, K.; Filip, P.; Finch, E.; Fisyak, Y.; Flierl, D.; Foley, K.J.; Fu, J.; Gagliardi, C.A.; Ganti, M.S.; Gutierrez, T.D.; Gagunashvili, N.; Gans, J.; Gaudichet, L.; Germain, M.; Geurts, F.; Ghazikhanian, V.; Ghosh, P.; Gonzalez, J.E.; Grachov, O.; Grigoriev, V.; Gronstal, S.; Grosnick, D.; Guedon, M.; Guertin, S.M.; Gupta, A.; Gushin, E.; Hallman, T.J.; Hardtke, D.; Harris, J.W.; Heinz, M.; Henry, T.W.; Heppelmann, S.; Herston, T.; Hippolyte, B.; Hirsch, A.; Hjort, E.; Hoffmann, G.W.; Horsley, M.; Huang, H.Z.; Huang, S.L.; Humanic, T.J.; Igo, G.; Ishihara, A.; Jacobs, P.; Jacobs, W.W.; Janik, M.; Johnson, I.; Jones, P.G.; Judd, E.G.; Kabana, S.; Kaneta, M.; Kaplan, M.; Keane, D.; Kiryluk, J.; Kisiel, A.; Klay, J.; Klein, S.R.; Klyachko, A.; Koetke, D.D.; Kollegger, T.; Konstantinov, A.S.; Kopytine, M.; Kotchenda, L.; Kovalenko, A.D.; Kramer, M.; Kravtsov, P.; Krueger, K.; Kuhn, C.; Kulikov, A.I.; Kumar, A.; et al.

    2004-01-08

    We report the first inclusive photon measurements about mid-rapidity (|y| < 0.5) from {sup 197}Au + {sup 197}Au collisions at {radical}s{sub NN} = 130 GeV at RHIC. Photon pair conversions were reconstructed from electron and positron tracks measured with the Time Projection Chamber (TPC) of the STAR experiment. With this method, an energy resolution of {Delta}E/E {approx} 2% at 0.5 GeV has been achieved. Reconstructed photons have also been used to measure the transverse momentum (p{sub t}) spectra of {pi}{sup 0} mesons about mid-rapidity (|y| < 1) via the {pi}{sup 0} {yields} {gamma}{gamma} decay channel. The fractional contribution of the {pi}{sup 0} {yields} {gamma}{gamma} decay to the inclusive photon spectrum decreases by 20% {+-} 5% between p{sub t} = 1.65 GeV/c and p{sub t} = 2.4 GeV/c in the most central events, indicating that relative to {pi}{sup 0} {yields} {gamma}{gamma} decay the contribution of other photon sources is substantially increasing.

  15. Neutron Radiative Capture Cross Section of {sup 232}Th in the Energy Range from 0.06 to 2 MeV

    SciTech Connect

    Karamanis, D.; Petit, M.; Andriamonje, S.; Barreau, G.; Bercion, M.; Billebaud, A.; Blank, B.; Czajkowski, S.; Moral, R. del; Giovinazzo, J.; Lacoste, V.; Marchand, C.; Perrot, L.; Pravikoff, M.; Thomas, J.C.

    2001-11-15

    The neutron capture cross section of {sup 232}Th has been measured relative to {sigma}(n, {gamma}) for {sup 197}Au and {sigma}(n,f) for {sup 235}U in the energy range from 60 keV to 2 MeV. Neutrons were produced by the {sup 7}Li(p,n) and T(p,n) reactions at the 4-MV Van de Graaff Accelerator of CEN Bordeaux-Gradignan. The activation technique was used, and the cross section was measured relative to the {sup 197}Au(n,{gamma}) standard cross section up to 1 MeV. The characteristic gamma lines of the product nuclei {sup 233}Pa and {sup 198}Au were measured with a 40% high-purity germanium detector. Above this energy, the reaction {sup 235}U(n,f) was also used as a second standard, and the fission fragments were detected with a photovoltaic cell. The results, after applying the appropriate corrections, indicate that the cross sections are close to the JENDL-3 database values up to 800 keV and over 1.4 MeV. For energies in the intermediate range, our values are slightly lower than those from all the libraries.

  16. Capture cross section measurement analysis in the Californium-252 spectrum with the Monte Carlo method.

    PubMed

    Manojlovič, Stanko; Trkov, Andrej; Žerovnik, Gašper; Snoj, Luka

    2015-07-01

    Absolute average capture cross sections of gold, thorium, tantalum, molybdenum, copper and strontium in (252)Cf spontaneous fission neutron spectrum were simulated for two types of experiment setups preformed by Z. Dezso and J. Csikai and by L. Green. The experiments were simulated with MCNP5 using cross section data from the ENDF/B-VII.0 library. The determination of neutron backscattering was calculated with the use of neutron flagging. Correction factors to experimentally measured values were determined to obtain average cross sections in a pure (252)Cf spontaneous fission spectrum. Influence of concrete wall thickness, air moisture and room size on the average cross section was analyzed. Correction factors amounted to about 30%. Corrected values corresponding to average cross sections in a pure (252)Cf spectrum were calculated for (197)Au, (232)Th, (181)Ta, (98)Mo, (65)Cu and (84)Sr. Average cross sections were also calculated with the RR_UNC software using IRDFF-v.1.05 and ENDF/B-VII.0 libraries. The revised average radiative capture cross sections are 75.5±0.1 mb for (197)Au, 87.0±1.6 mb for (232)Th , 98.0±4.5 mb for (181)Ta, 21.2±0.5 mb for (98)Mo, 10.3±0.3 mb for (63)Cu, and 34.9±6.5 mb for (84)Sr. PMID:25880611

  17. Constraining the high-density behavior of the nuclear equation of state from strangeness production in heavy-ion collisions

    SciTech Connect

    Feng Zhaoing

    2011-06-15

    The dynamics of pions and strange particles in heavy-ion collisions in the region of 1A GeV energies is investigated by the lanzhou quantum molecular dynamics model for probing the nuclear equation of state at suprasaturation densities. The total multiplicities and the ratios obtained in {sup 197}Au+{sup 197}Au over {sup 12}C+{sup 12}C systems are calculated for selected Skyrme parameters SkP, SLy6, Ska, and SIII, which correspond to different modulus of incompressibility of symmetric nuclear matter and different cases of the stiffness of symmetry energy. A decreasing trend of the excitation functions of the ratios for strange particle production with increasing incident energy was observed. The available data of K{sup +} production measured by KaoS collaboration are described well with the parameter SkP, which results in a soft equation of state. The conclusions cannot be modified by an in-medium kaon-nucleon potential.

  18. Characterization of the multifragment decay channel in highly excited nuclei. [Indiana Univ. , Bloomington, Indiana

    SciTech Connect

    de Souza, R.T.

    1992-10-01

    Characteristics of multifragment decay in heavy-ion induced reactions at intermediate energies are explored. Evolution of the timescale for emission of intermediate mass fragments (IMF: 3[le]Z[le]20) is investigated. Fragments associated with central collisions in the reactions [sup 36]Ar + [sup 197]Au at E/A = 50, 80, and 110 MeV are emitted on an extremely fast timescale, [tau] [le] 75 fm/c, comparable to the transit time of the projectile past the target nucleus. With increasing incident energy, mean fragment emission times decrease, consistent with statistical decay from highly excited systems or fast dynamical processes. To examine the importance of expansion effects in multifragmentation, the transverse kinetic energy of fragments was investigated. Evidence for expansion effects in the system [sup 36]Ar + [sup 197]Au at E/A = 50, 80, and 110 MeV was indicated by the charge dependence of the mean isotropic kinetic energy. At the highest incident energy the data suggest the onset of volume emission. Construction and performance of low-threshold high-resolution detector telescopes is discussed. Three-body Coulomb trajectory calculations are being used to probe kinematical correlations associated with neck emission of IMFs during fission. Initial design and testing of position sensitive parallel plate avalanche counters for upcoming ternary fission experiments is discussed.

  19. Characterization of the multifragment decay channel in highly excited nuclei. Progress report, March 15, 1992--September 14, 1993

    SciTech Connect

    de Souza, R.T.

    1992-10-01

    Characteristics of multifragment decay in heavy-ion induced reactions at intermediate energies are explored. Evolution of the timescale for emission of intermediate mass fragments (IMF: 3{le}Z{le}20) is investigated. Fragments associated with central collisions in the reactions {sup 36}Ar + {sup 197}Au at E/A = 50, 80, and 110 MeV are emitted on an extremely fast timescale, {tau} {le} 75 fm/c, comparable to the transit time of the projectile past the target nucleus. With increasing incident energy, mean fragment emission times decrease, consistent with statistical decay from highly excited systems or fast dynamical processes. To examine the importance of expansion effects in multifragmentation, the transverse kinetic energy of fragments was investigated. Evidence for expansion effects in the system {sup 36}Ar + {sup 197}Au at E/A = 50, 80, and 110 MeV was indicated by the charge dependence of the mean isotropic kinetic energy. At the highest incident energy the data suggest the onset of volume emission. Construction and performance of low-threshold high-resolution detector telescopes is discussed. Three-body Coulomb trajectory calculations are being used to probe kinematical correlations associated with neck emission of IMFs during fission. Initial design and testing of position sensitive parallel plate avalanche counters for upcoming ternary fission experiments is discussed.

  20. Covariances Obtained from an Evaluation of the Neutron Cross Section Standards

    SciTech Connect

    Carlson, A. D.; Badikov, S. A.; Chen, Zhenpeng; Gai, E.; Pronyaev, V. G.; Hale, G. M.; Kawano, T.; Hambsch, F.; Hoffman, H.; Larson, Nancy M; Oli, S.; Smith, D. L.; Tagesen, S.; Vonach, H.

    2008-12-01

    New measurements and an improved evaluation process were used to obtain a new evaluation of the neutron cross section standards. Efforts were made to include as much information as possible on the components of the data uncertainties that were then used to obtain the covariance matrices for the experimental data. Evaluations were produced from this process for the 6Li(n,t), 10B(n, ), 10B(n, 1 ), 197Au(n, ), 235U(n,f), and 238U(n,f) standard cross sections as well as the non-standard 6Li(n,n), 10B(n,n), 238U(n, ) and 239Pu(n,f) cross sections. There is a general increase in the cross sections for most of the new evaluations, by as much as about 5%, compared with the ENDF/B-VI results. Covariance data were obtained for the 6Li(n,t), 6Li(n,n), 10B(n, ), 10B(n, 1 ), 10B(n,n), 197Au(n, ), 235U(n,f), 238U(n,f), 238U(n, ) and 239Pu(n,f) reactions. Also an independent R-Matrix evaluation was produced for the H(n,n) standard cross-section, however, covariance data are not available for this reaction. The evaluations were used in the new ENDF/B-VII library.

  1. Analysis of precious metals at parts-per-billion levels in industrial applications

    NASA Astrophysics Data System (ADS)

    Tickner, James; O'Dwyer, Joel; Roach, Greg; Smith, Michael; Van Haarlem, Yves

    2015-11-01

    Precious metals, including gold and the platinum group metals (notable Pt, Pd and Rh), are mined commercially at concentrations of a few parts-per-million and below. Mining and processing operations demand sensitive and rapid analysis at concentrations down to about 100 parts-per-billion (ppb). In this paper, we discuss two technologies being developed to meet this challenge: X-ray fluorescence (XRF) and gamma-activation analysis (GAA). We have designed on-stream XRF analysers capable of measuring targeted elements in slurries with precisions in the 35-70 ppb range. For the past two years, two on-stream analysers have been in continuous operation at a precious metals concentrator plant. The simultaneous measurement of feed and waste stream grades provides real-time information on metal recovery, allowing changes in operating conditions and plant upsets to be detected and corrected more rapidly. Separately, we have been developing GAA for the measurement of gold as a replacement for the traditional laboratory fire-assay process. High-energy Bremsstrahlung X-rays are used to excite gold via the 197Au(γ,γ‧)197Au-M reaction, and the gamma-rays released in the decay of the meta-state are then counted. We report on work to significantly improve accuracy and detection limits.

  2. Nuclear chemistry. Progress report, September 1, 1980-July 31, 1981

    SciTech Connect

    Loveland, W.D.

    1981-07-01

    This is a report of progress on the study of low-energy, intermediate-energy, and relativistic heavy-ion reactions. Data in particular are presented for: /sup 44/Sc isomer ratio in /sup 29/Si(/sup 18/O,p2n) reaction; fragment angular distributions in reaction of 86 MeV/..mu.. /sup 12/C with /sup 197/Au and /sup 238/U; fragment recoil properties in reaction of 50 to 86 MeV/..mu.. /sup 12/C with /sup 181/Ta and /sup 197/Au; target fragmentation in heavy ion reactions with Au; fragment yields and mass distributions in reactions of /sup 20/Ne, /sup 12/C, and protons with /sup 181/Ta and /sup 238/U; fragment angular momenta of precursor of /sup 44/Sc produced in reaction of 25-GeV /sup 12/C and 80-GeV /sup 40/Ar with Cu; fragmentation of /sup 165/Ho by /sup 12/C and protons at various energies; and energy dependence of the total cross section of /sup 20/Ne + /sup 181/Ta reaction. Reprints and preprints are included in the appendix. (DLC)

  3. Fabrication of {198Au0} radioactive composite nanodevices and their use for nano-brachytherapy

    PubMed Central

    Khan, Mohamed K.; Minc, Leah D.; Nigavekar, Shraddha S.; Kariapper, Muhammed S. T.; Nair, Bindu M.; Schipper, Matthew; Cook, Andrew C.; Lesniak, Wojciech G.; Balogh, Lajos P.

    2008-01-01

    We describe the simple fabrication of poly({198Au}) radioactive gold/dendrimer composite nanodevices in distinct sizes (between d=10 nm and 29 nm) for targeted radiopharmaceutical dose delivery to tumors in vivo. Irradiation of aqueous solutions of 197Au containing poly(amidoamine) dendrimer tetrachloroaurate salts or {197Au0} gold/dendrimer nanocomposites in a nuclear reactor resulted in the formation of positively charged and soluble poly{198Au0} radioactive composite nanodevices (CNDs). A mouse melanoma tumor model was used to test the poly{198Au0} CNDs whether they can deliver a therapeutic dose. A single intratumoral injection of poly{198Au0}d=22nm CNDs in PBS delivering a dose of 74 microCi, after eight days, resulted in a statistically significant 45% reduction in tumor volume, when compared to untreated groups and those injected with the “cold” nanodevice. No clinical toxicity was observed during the experiments. This study provides the first proof of principle that radioactive composite nanodevices can deliver therapeutic doses to tumors. PMID:18249156

  4. Aspergillus infection monitored by multimodal imaging in a rat model.

    PubMed

    Pluhacek, Tomas; Petrik, Milos; Luptakova, Dominika; Benada, Oldrich; Palyzova, Andrea; Lemr, Karel; Havlicek, Vladimir

    2016-06-01

    Although myriads of experimental approaches have been published in the field of fungal infection diagnostics, interestingly, in 21st century there is no satisfactory early noninvasive tool for Aspergillus diagnostics with good sensitivity and specificity. In this work, we for the first time described the fungal burden in rat lungs by multimodal imaging approach. The Aspergillus infection was monitored by positron emission tomography and light microscopy employing modified Grocott's methenamine silver staining and eosin counterstaining. Laser ablation inductively coupled plasma mass spectrometry imaging has revealed a dramatic iron increase in fungi-affected areas, which can be presumably attributed to microbial siderophores. Quantitative elemental data were inferred from matrix-matched standards prepared from rat lungs. The iron, silver, and gold MS images collected with variable laser foci revealed that particularly silver or gold can be used as excellent elements useful for sensitively tracking the Aspergillus infection. The limit of detection was determined for both (107) Ag and (197) Au as 0.03 μg/g (5 μm laser focus). The selective incorporation of (107) Ag and (197) Au into fungal cell bodies and low background noise from both elements were confirmed by energy dispersive X-ray scattering utilizing the submicron lateral resolving power of scanning electron microscopy. The low limits of detection and quantitation of both gold and silver make ICP-MS imaging monitoring a viable alternative to standard optical evaluation used in current clinical settings. PMID:27060291

  5. Non-equilibrium fission processes in intermediate energy nuclear collisions

    SciTech Connect

    Loveland, W.; Casey, C.; Xu, Z.; Seaborg, G.T.; Aleklett, K.; Sihver, L.

    1989-04-01

    We have measured the target fragment yields, angular and energy distributions for the interaction of 12-16 MeV/A/sup 32/S with /sup 165/Ho and /sup 197/Au and for the interaction of 32 and 44 MeV/A /sup 40/Ar with /sup 197/Au. The Au fission fragments associated with the peripheral collision peak in the folding angle distribution originate in a normal, ''slow'' fission process in which statistical equilibrium has been established. At the two lowest projectile energies, the Au fission fragments associated with the central collision peak in the folding angle distribution originate in part from ''fast'' (/tau//approximately//sup /minus/23/s), non-equilibrium processes. Most of the Ho fission fragments originate in non- equilibrium processes. The fast, non-equilibrium process giving rise to these fragments has many of the characteristics of ''fast fission'', but the cross sections associated with these fragments are larger than one would expect from current theories of ''fast fission. '' 14 refs., 8 figs.

  6. A study on the Fresnel diffraction of {sup 6}He by means of different microscopic density distributions

    SciTech Connect

    Aygun, M.; Boztosun, I.; Sahin, Y.

    2012-08-15

    The elastic scattering of the halo nucleus {sup 6}He from heavy targets such as {sup 197}Au and {sup 208}Pb has been investigated in order to explain the Coulomb rainbow peak due to the Fresnel-type diffraction observed in the experimental data. In order to examine the role of nuclear potential to describe {sup 6}He + {sup 197}Au and {sup 6}He + {sup 208}Pb systems, we have used the no-core shell model, few-body and Gaussian-shaped density distributions at various energies. The microscopic real parts of the complex nuclear potential have been obtained by using the double-folding model for each of the density distribution and the phenomenological imaginary potentials have been taken as the standard Woods-Saxon shape. We have observed that fewbody and Gaussian-shaped density distributions have given standard Fresnel-type diffraction results, a classical scattering pattern with Coulomb rainbow peak whereas the nuclear potential obtained by using the no-core shell-model density distribution has provided the reduction at Fresnel peak and has given more consistent results with the experimental data.

  7. Measurement of the keV-neutron capture cross section and capture gamma-ray spectrum of isotopes around N=82 region

    SciTech Connect

    Katabuchi, Tatsuya; Igashira, Masayuki

    2012-11-12

    The keV-neutron capture cross section and capture {gamma}-ray spectra of nuclides with a neutron magic number N= 82, {sup 139}La and {sup 142}Nd, were newly measured by the time-of-flight method. Capture {gamma}-rays were detected with an anti-Compton NaI(T1) spectrometer, and the pulse-height weighting technique was applied to derive the neutron capture cross section. The results were provided with our previous measurements of other nuclides around N= 82, {sup 140}Ce, {sup 141}Pr, {sup 143}Nd and {sup 145}Nd.

  8. Production and decay spectroscopy of 192Po and 194Po

    NASA Astrophysics Data System (ADS)

    Andel, B.

    2015-10-01

    A γ-ray spectroscopy study of the (11-) isomers in 194Po and 192Po was performed at the velocity filter SHIP at GSI (Germany). Nuclei were produced in fusion-evaporation reactions and investigated in the detection set-up at the focal plane after the separator. Several new γ transitions were attributed to the isomers and detailed analysis of the first γ-γ coincidences for both isomers is being prepared. For the reaction 56Fe + 141Pr → 197At*, excitation functions for astatine and polonium isotopes were measured and compared with HIVAP calculations.

  9. Production and decay spectroscopy of {sup 192}Po and {sup 194}Po

    SciTech Connect

    Andel, B.

    2015-10-15

    A γ-ray spectroscopy study of the (11{sup −}) isomers in {sup 194}Po and {sup 192}Po was performed at the velocity filter SHIP at GSI (Germany). Nuclei were produced in fusion-evaporation reactions and investigated in the detection set-up at the focal plane after the separator. Several new γ transitions were attributed to the isomers and detailed analysis of the first γ-γ coincidences for both isomers is being prepared. For the reaction {sup 56}Fe + {sup 141}Pr → {sup 197}At*, excitation functions for astatine and polonium isotopes were measured and compared with HIVAP calculations.

  10. Investigations of Extreme Subbarrier Fission of URANIUM-235

    NASA Astrophysics Data System (ADS)

    Narayanan, Arjun

    An efficient detection setup has been devised for the measurement of thick target fission yields in coincidence with gamma-rays. Based on a new and versatile detector (PVD - Photo Voltaic Device), this arrangement has the sensitivity to detect fission events with cross sections of the order of 10^ {-9} barns (10^{-33 } cm^2) with a fragment -gamma coincidence detection efficiency of 40%. A computer code (PONTF) has been developed in order to simulate this detector geometry as well as effects of the thick target, thus enabling the translation of thick target yields to cross sections. For the reaction system 4-12 MeV ^1 H + ^{238}{U }, it was found that this arrangement was insensitive to backscattered protons and the thick target fission fragment energy spectra compared very well with spectra simulated by PONTF. The fission of ^{235} U in the deep sub-barrier region has also been investigated using 200 MeV ^{197}Au and 20-80 MeV ^{12}C projectiles. Multiple Coulomb excitation computer codes (COULEX and GOSIA) have been used to investigate the possibility of the fission of ^{235}U following Coulomb excitation. The first study used the reaction system 200 MeV ^{197}Au + ^ {235}U. No fission fragments were observed in coincidence with gamma-rays for ~10^{14} incident projectiles. The excitation function for the fission of ^{235}U induced by ^{12}C was measured for projectiles with energies of 20-80 MeV. An enhancement was observed over the extrapolated fusion-fission yields for beam energies below 55 MeV. Deduced branching ratios have been compared for the four experimental systems (1) 1.5-2.5 MeV ^1H + ^{235}U, (2) 3-4 Mev ^4He ^ {235}U, (3) 200 MeV ^{197 }Au + ^{235}U and (4) 20-55 MeV ^{12}C ^{235}U. These values were compared to test the hypothesis that one level in ^{235}U, with a large fission branch, was solely responsible for the cross section enhancement in the deep sub-barrier region. This hypothesis is not consistent with the data and we conclude that more

  11. Pre-equilibrium studies in monoisotopic praseodymium

    SciTech Connect

    Singh, B.P.; Mustafa, M.M.; Sankarcharyulu, M.G.V.

    1994-12-31

    Measurement and analysis of excitation functions in {alpha}-induced reactions has become an important tool for studying the pre-equilibrium (PE) phenomenon. As part of the programme of precise measurement and analysis of excitation functions in reactions for a large number of nuclei, the authors report the measurement of excitation functions for the reactions {sup 141}Pr({alpha},n){sup 144}Pm and {sup 141}Pr({alpha},2n){sup 143}Pm in the energy range from threshold to {approx}40 MeV. To the best of their knowledge, these excitation functions have been measured for the first time. Measurements have been performed using stacked foil activation technique. The irradiation has been carried out at the Variable Energy Cyclotron Centre (VECC), Calcutta, India using the {alpha}-beam of {approx} 40 MeV. The post irradiation analysis has been done using the HPGe detector coupled to the ORTEC`s PC based multichannel analyser. The analysis of the excitation functions has been carried out using the semi-classical computer codes ACT and ALICE-82. These codes use Hauser-Feshbach/ Welsskopf-Ewing formalism for compound nucleus calculations and exciton/hybrid model for simulating PE contributions. The quantum mechanical statistical multistep code EXIFON has also been used for the analysis of these excitation functions. The comparison of results with different codes will be presented.

  12. Spin-spin cross relaxation and spin-Hamiltonian spectroscopy by optical pumping of Pr/sup 3+/:LaF/sub 3/

    SciTech Connect

    Lukac, M.; Otto, F.W.; Hahn, E.L.

    1989-02-01

    We report the observation of an anticrossing in solid-state laser spectroscopy produced by cross relaxation. Spin-spin cross relaxation between the /sup 141/Pr- and /sup 19/F-spin reservoirs in Pr/sup 3+/:LaF/sub 3/ and its influence on the /sup 141/Pr NMR spectrum is detected by means of optical pumping. The technique employed combines optical pumping and hole burning with either external magnetic field sweep or rf resonance saturation in order to produce slow transient changes in resonant laser transmission. At a certain value of the external Zeeman field, where the energy-level splittings of Pr and F spins match, a level repulsion and discontinuity of the Pr/sup 3+/ NMR lines is observed. This effect is interpreted as the ''anticrossing'' of the combined Pr-F spin-spin reservoir energy states. The Zeeman-quadrupole-Hamiltonian spectrum of the hyperfine optical ground states of Pr/sup 3+/:LaF/sub 3/ is mapped out over a wide range of Zeeman magnetic fields. A new scheme is proposed for dynamic polarization of nuclei by means of optical pumping, based on resonant cross relaxation between rare spins and spin reservoirs.

  13. Spin Hamiltonian Spectroscopy in PRASEODYMIUM(3):LANTHANUM Trifluoride.

    NASA Astrophysics Data System (ADS)

    Otto, Frederick William

    An optically detected anticrossing in solid state laser spectroscopy produced by cross-relaxation is reported. Spin -spin cross-relaxation between the ^{141 }Pr and ^{19}F spin reservoirs in Pr^{+3}:LaF _3 and its influence on the ^{141}Pr NMR spectrum is observed. The detection technique employed combines optical pumping and hole burning with either an external magnetic field sweep or rf resonance saturation producing slow transient changes in resonant laser transmission. At a certain value of the external magnetic field, where the energy level splittings of Pr and F spins match, a level repulsion and discontinuity of the Pr^{+3} NMR lines is observed. This effect is interpreted as the "anticrossing" of the combined Pr-F spin-spin reservoir energy states. The Zeeman - Quadrupole Hamiltonian spectrum of the lowest hyperfine optical ground state manifold of Pr^ {+3}:LaF_3 is mapped out over a wide range of Zeeman magnetic fields. A new method is proposed for dynamically polarizing nuclei by means of optical pumping, using resonant cross-relaxation between rare spins and spin reservoirs.

  14. Neutrons scattering studies in the actinide region. Progress report, August 1, 1991--July 31, 1992

    SciTech Connect

    Kegel, G.H.R.; Egan, J.J.

    1992-09-01

    During the report period were investigated the following areas: prompt fission neutron energy spectra measurements; neutron elastic and inelastic scattering from {sup 239}Pu; neutron scattering in {sup 181}Ta and {sup 197}Au; response of a {sup 235}U fission chamber near reaction thresholds; two-parameter data acquisition system; ``black`` neutron detector; investigation of neutron-induced defects in silicon dioxide; and multiple scattering corrections. Four Ph.D. dissertations and one M.S. thesis were completed during the report period. Publications consisted of three journal articles, four conference papers in proceedings, and eleven abstracts of presentations at scientific meetings. There are currently four Ph.D. and one M.S. candidates working on dissertations directly associated with the project. In addition, three other Ph.D. candidates are working on dissertations involving other aspects of neutron physics in this laboratory.

  15. Neutrons scattering studies in the actinide region

    SciTech Connect

    Kegel, G.H.R.; Egan, J.J.

    1992-09-01

    During the report period were investigated the following areas: prompt fission neutron energy spectra measurements; neutron elastic and inelastic scattering from [sup 239]Pu; neutron scattering in [sup 181]Ta and [sup 197]Au; response of a [sup 235]U fission chamber near reaction thresholds; two-parameter data acquisition system; black'' neutron detector; investigation of neutron-induced defects in silicon dioxide; and multiple scattering corrections. Four Ph.D. dissertations and one M.S. thesis were completed during the report period. Publications consisted of three journal articles, four conference papers in proceedings, and eleven abstracts of presentations at scientific meetings. There are currently four Ph.D. and one M.S. candidates working on dissertations directly associated with the project. In addition, three other Ph.D. candidates are working on dissertations involving other aspects of neutron physics in this laboratory.

  16. Thermal flucatuations in a classical theory with shape degrees of freedom for heavy ion collisions

    NASA Astrophysics Data System (ADS)

    Samaddar, S. K.; Sperber, D.; Zielińska-Pfabe, M.; Sobel, M. I.; Garpman, S. I.

    1981-02-01

    We use a classical dynamical theory with shape degrees of freedom to describe deep inelastic scattering of heavy ions, and include thermal fluctuations by means of the Fokker-Planck equation. The degrees of freedom allow for neck formation, mass transfer, and stretching of the two-nucleus system. Inertias are calculated for these degrees of freedom, and dissipative and conservative forces are used. Fluctuations are calculated by considering the second moments of the distribution and determining a temperature from the excitation energy at each time. We calculate distributions in final energy, angle, charge, and mass, including some double differential cross sections. Results are in good agreement with data. NUCLEAR REACTIONS Classical dynamical model, shape degrees of freedom, Fokker-Planck equation, thermal fluctuations; angular, energy, mass, and charge distributions are calculated for the reactions 209Bi + 84Kr, 209Bi + 136Xe, and 197Au + 63Cu.

  17. Study of the reactions occurring in the fusion of {sup 12}C and {sup 16}O with heavy nuclei at incident energies below 10 MeV/nucleon

    SciTech Connect

    Cavinato, M.; Fabrici, E.; Gadioli, E.; Gadioli Erba, E.; Vergani, P.; Crippa, M.; Colombo, G.; Redaelli, I.; Ripamonti, M.

    1995-11-01

    The excitation functions for production of many residues in the fusion of {sup 12}C with {sup 181}Ta and {sup 197}Au and of {sup 16}O with {sup 165}Ho and {sup 181}Ta have been measured at incident energies varying from the Coulomb barrier up to about 10 MeV/nucleon. The cross sections for fusion of these ions without fission have been deduced and they show that such a process may only occur for projectile angular momenta smaller than a critical value. The excitation functions for individual reactions provide evidence for the emission of preequilibrium nucleons during the thermalization of the composite nucleus and may be satisfactorily reproduced by a calculation based on the Boltzmann master equation theory.

  18. Measurement of Nuclear Transparency for the A(e,e' pi^+) Reaction

    SciTech Connect

    B. Clasie; X. Qian; J. Arrington; R. Asaturyan; F. Benmokhtar; W. Boeglin; P. Bosted; A. Bruell; M. E. Christy; E. Chudakov; W. Cosyn; M. M. Dalton; A. Daniel; D. Day; D. Dutta; L. El Fassi; R. Ent; H. C. Fenker; J. Ferrer; N. Fomin; H. Gao; K. Garrow; D. Gaskell; C. Gray; T. Horn; G. M. Huber; M. K. Jones; N. Kalantarians; C. E. Keppel; K. Kramer; A. Larson; Y. Li; Y. Liang; A. F. Lung; S. Malace; P. Markowitz; A. Matsumura; D. G. Meekins; T. Mertens; G. A. Miller; T. Miyoshi; H. Mkrtchyan; R. Monson; T. Navasardyan; G. Niculescu; I. Niculescu; Y. Okayasu; A. K. Opper; C. Perdrisat; V. Punjabi; A. W. Rauf; V. M. Rodriquez; D. Rohe; J. Ryckebusch; J. Seely; E. Segbefia; G. R. Smith; M. Strikman; M. Sumihama; V. Tadevosyan; L. Tang; V. Tvaskis; A. Villano; W. F. Vulcan; F. R. Wesselmann; S. A. Wood; L. Yuan; X. C. Zheng

    2007-12-01

    We have measured the nuclear transparency of the A(e,e' pi^+) process in ^{2}H,^{12}C, ^{27}Al, ^{63}Cu and ^{197}Au targets. These measurements were performed at the Jefferson Laboratory over a four momentum transfer squared range Q^2 = 1.1 - 4.7 (GeV/c)^2. The nuclear transparency was extracted as the super-ratio of $(\\sigma_A/\\sigma_H)$ from data to a model of pion-electroproduction from nuclei without pi-N final state interactions. The Q^2 and atomic number dependence of the nuclear transparency both show deviations from traditional nuclear physics expectations, and are consistent with calculations that include the quantum chromodynamical phenomenon of color transparency.

  19. Recent developments of SOLEROO: Australia's first high energy radioactive Ion Beam capability

    NASA Astrophysics Data System (ADS)

    Carter, I. P.; Dasgupta, M.; Hinde, D. J.; Luong, D. H.; Williams, E.; Ramachandran, K.; Cook, K. J.; Muirhead, A. G.; Marshall, S.; Tunningley, T.

    2015-04-01

    The first measurements of the Australian National University's new radioactive ion beam capability were carried out using elastic scattering of a 8Li radioactive beam from a 197Au target. The purpose of this experiment was to test the radioactive ion beam capability as a complete system, which uses a pair of twin position-sensitive parallel plate avalanche counters as tracking detectors along with a highly pixelated double sided Si detector array. The tracking detector system allows us to have extremely high purity secondary radioactive ion beams by electronically tagging the reaction products of interest, thus allowing complete separation from the unwanted contaminant beam species of similar mass and charge. Here, some recent developments and characteristics of this system are presented.

  20. The simultaneous evaluation of the standards and other cross sections of importance for technology

    SciTech Connect

    Poenitz, W.P.; Aumeier, S.E.

    1997-09-01

    The simultaneous evaluation of the cross sections of {sup 6}Li(n,{alpha}), {sup 6}Li(n,n), {sup 10}B(n,{alpha}{sub 0}), {sup 10}B(n,{alpha}{sup 1}), {sup 10}B(n,n), {sup 197}Au(n,{gamma}), {sup 238}U(n,{gamma}), {sup 235}U(n,f), {sup 239}Pu(n,f), and {sup 238}U(n,f) and the thermal constants was part of the evaluation of these data for ENDF/B-VI The FORTRAN codes and the data files used for the simultaneous evaluation are documented in the present report. Corrections for some data reported in the literature and the addition of several new data sets results in negligible changes except for the fission cross sections where minor changes occur relative to the evaluation for ENDF/B-VI.

  1. Nuclear research with heavy ions. Annual progress report. January 1, 1980-December 31, 1980

    SciTech Connect

    Kaplan, M.

    1980-10-01

    The program of research is oriented towards experimental studies of the interactions between heavy ions and complex nuclei. These interactions are probed by detailed measurements of light-charged-particle emission using counter telescopes for atomic number and mass number identification. Singles measurements of the charged-particle energy spectra and angular distributions, together with coincidence correlations with heavy nuclear-reaction fragments, provide insight into the contributing reaction mechanisms. The application of the statistical model to the appropriate experimental data allows the determination of parameters necessary to calibrate the theory, and gives indications of dynamical control vs. equilibrium in the several degrees of freedom associated with the nuclear collisions. A large body of data are presented and discussed for /sup 40/Ar reactions with /sup 116/Sn, /sup 154/Sm, /sup 164/Dy, and /sup 197/Au targets. Complete results are also given for twelve reactions which produce /sup 194/Hg compound nuclei at several excitation energies.

  2. Inclusive electron scattering from nuclei in the quasielastic region at large momentum transfer

    NASA Astrophysics Data System (ADS)

    Fomin, Nadia

    2008-12-01

    Experiment E02-019, performed in Hall C at the Thomas Jefferson National Accelerator Facility (TJNAF), was a measurement of inclusive electron cross sections for several nuclei (^{2}H,^{3}He, ^{4}He, ^{9}Be,^{12}C, ^{63}Cu, and ^{197}Au) in the quasielastic region at high momentum transfer. In the region of low energy transfer, the cross sections were analyzed in terms of the reduced response, F(y), by examining its y-scaling behavior. The data were also examined in terms of the nuclear structure function ν W_2^A and its behavior in x and the Nachtmann variable ξ. The data show approximate scaling of ν W_2^A in ξ for all targets at all kinematics, unlike scaling in x, which is confined to the DIS regime. However, y-scaling observations are limited to the kinematic region dominated by the quasielastic response ({y<0}), where some scaling violations arising from FSIs are observed.

  3. Asymmetry effects in fragment production

    NASA Astrophysics Data System (ADS)

    Kaur, Manpreet; Kaur, Varinderjit

    2016-05-01

    The production of different fragments has been studied by taking into account the mass asymmetry of the reaction and employing the momentum dependent interactions. Two different set of asymmetric reactions have been analyzed while keeping Atotal fixed using soft momentum dependent equation of state. Our results indicate that the impact of momentum dependent interactions is different in lighter projectile systems as compared to heavier ones. The comparative analysis of IQMD simulations with the experimental data in case of heavier projectile and lighter target system for the reaction of 197Au+27Al (η = 0.7) at E = 600 MeV/nucleon shows that with the inclusion of MDI we are able, upto some extent, to reproduce the experimental universality of rise and fall of intermediate mass fragments (IMFs).

  4. Relativistic heavy ion physics. Progress report, November 15, 1992--November 14, 1993

    SciTech Connect

    Hill, J.C.; Wohn, F.K.

    1993-11-01

    This is a progress report for the period May 1992 through April 1993. The first section, entitled ``Purpose and Trends, gives background on the recent trends in the research program and its evolution from an emphasis on nuclear structure physics to its present emphasis on relativistic heavy ion and RHIC physics. The next section, entitled ``Physics Research Progress``, is divided into four parts: participation in the program to develop a large detector named PHENIX for the RHIC accelerator; joining E864 at the AGS accelerator and the role in that experiment; progress made in the study of electromagnetic dissociation highlight of this endeavor is an experiment carried out with the {sup 197}Au beam from the AGS accelerator in April 1992; progress in completion of the nuclear structure studies. In the final section a list of publications, invited talks, and contributed talks is given.

  5. Neutron capture cross-section measurement for the 186W(n,gamma)187W reaction at 0.0536eV energy.

    PubMed

    Uddin, M S; Chowdhury, M H; Hossain, S M; Latif, Sk A; Hafiz, M A; Islam, M A; Zakaria, A K M; Azharul Islam, S M

    2008-09-01

    The thermal neutron-induced activation cross section for the (186)W(n,gamma)(187)W reaction was measured at 0.0536eV neutron energy using TRIGA Mark-II research reactor, Atomic Energy Research Establishment, Savar, Dhaka, Bangladesh. The (197)Au(n,gamma)(198)Au monitor reaction induced in a high-purity gold foil was used to determine the effective neutron beam intensity. The activities induced in sample and monitor foils were measured nondestructively by a high-resolution HPGe gamma-ray detector. The present experimental cross-section value is the first one at 0.0536eV. The obtained new cross section that amounts to 26.6+/-1.6b is 2% higher than the recently reported data in ENDF/B-VII and 5% lower than that of JENDL-3.3. PMID:18325774

  6. Experimental cross section of the 71Ga(n,γ)72Ga reaction at 0.0334 eV energy

    NASA Astrophysics Data System (ADS)

    Afroze, N.; Uddin, M. S.; Hossain, S. M.; Islam, M. A.; Shariff, M. A.; Zakaria, A. K. M.; Datta, T. K.; Azharul Islam, S. M.

    2014-10-01

    The cross section of the 71Ga(n,γ)72Ga reaction at 0.0334 eV was measured for the first time using monochromatic neutrons from powder diffractometer at TRIGA Mark II nuclear reactor. The 197Au(n,γ)198Au reaction was used to monitor the neutron beam intensity. The HPGe γ-ray spectrometry was used to determine the radioactivity of the product radionuclides. The obtained cross section value amounted 3.42 ± 0.27 b is about 95% consistent with JENDL-4, but about 17% and 14% lower than that of the ENDF/B-VII and TENDL-2012 data libraries, respectively. The measured value at 0.0334 eV and the previous measured value at 0.0536 eV would be useful to confirm the reliability of the data evaluated by 1/v relation in the above libraries.

  7. Vortex Pinning of Anisotropically Splayed Defects in YBa{sub 2}Cu{sub 3}O {sub 7{minus}{ital {delta}}}

    SciTech Connect

    Kwok, W.K.; Paulius, L.M.; Vinokur, V.M.; Petrean, A.M.; Ronningen, R.M.; Crabtree, G.W.

    1998-01-01

    Pinning by splayed defects created by 3.9GeV {sup 197}Au{sup 29+} ions is studied using transport measurements of vortex motion perpendicular and parallel to the splay plane in untwinned crystals of YBa{sub 2}Cu{sub 3}O{sub 7{minus}{delta}} . We compare the transport properties of the crystals and demonstrate (i) a new 1/H dependence of the vortex liquid pinning energy, (ii)a crossing of the irreversibility lines before and after irradiation, and (iii)a stronger temperature dependence of the critical current for vortex motion perpendicular to the splay plane than for motion parallel to the splay plane. {copyright} {ital 1998} {ital The American Physical Society}

  8. Observation of two-{alpha} emission from high-lying excited states of {sup 18}Ne by complete-kinematics measurements

    SciTech Connect

    Xu, X. X.; Lin, C. J.; Jia, H. M.; Yang, F.; Jia, F.; Wu, Z. D.; Zhang, S. T.; Liu, Z. H.; Zhang, H. Q.; Xu, H. S.; Sun, Z. Y.; Wang, J. S.; Hu, Z. G.; Wang, M.; Chen, R. F.; Zhang, X. Y.; Li, C.; Lei, X. G.; Xu, Z. G.; Xiao, G. Q.

    2010-12-15

    Two-{alpha} emission from high-lying excited states of {sup 18}Ne was studied by complete-kinematics measurements. The {sup 18}Ne beam at the energy of 51.8 MeV/u was bombarding a {sup 197}Au target to populate the excited states via Coulomb excitation. Products of two-{alpha} emission, {sup 10}C-{alpha}-{alpha}, were measured by an array of silicon strip detectors and a CsI + PIN telescope. With the help of Monte Carlo simulations, the experimental results show the characteristics of sequential two-{alpha} emission via {sup 14}O excited states. Sequential two-{alpha} and two-proton emissions from {sup 18}Ne via one-particle daughter states are compared and the distinction of the opening angles of these two modes originates from the difference of the mass ratio of emitted particles to daughter nuclei.

  9. Accuracy studies with carbon clusters at the Penning trap mass spectrometer TRIGA-TRAP

    NASA Astrophysics Data System (ADS)

    Ketelaer, J.; Beyer, T.; Blaum, K.; Block, M.; Eberhardt, K.; Eibach, M.; Herfurth, F.; Smorra, C.; Nagy, Sz.

    2010-05-01

    Extensive cross-reference measurements of well-known frequency ratios using various sizes of carbon cluster ions 12Cn + (10≤n≤23) were performed to determine the effects limiting the accuracy of mass measurements at the Penning-trap facility TRIGA-TRAP. Two major contributions to the uncertainty of a mass measurement have been identified. Fluctuations of the magnetic field cause an uncertainty in the frequency ratio due to the required calibration by a reference ion of uf(νref)/νref = 6(2) × 10-11/min × Δt. A mass-dependent systematic shift of the frequency ratio of epsilonm(r)/r = -2.2(2) × 10-9 × (m-mref)/u has been found as well. Finally, the nuclide 197Au was used as a cross-check since its mass is already known with an uncertainty of 0.6 keV.

  10. On the Balance Energy and Nuclear Dynamics in Peripheral Heavy-Ion Collisions

    NASA Astrophysics Data System (ADS)

    Chugh, Rajiv; Puri, Rajeev K.

    We present here the system size dependence of balance energy for semi-central and peripheral collisions using quantum molecular dynamics model. For this study, the reactions of Ne20+Ne20, Ca40+Ca40, Ni58+ Ni58, Nb93+Nb93, Xe131+Xe131, and Au197+Au197 are simulated at different incident energies and impact parameters. A hard equation of state along with nucleon-nucleon cross-sections between 40 and 55 mb explains the data nicely. Interestingly, balance energy follows a power law ∝Aτ for the mass dependence at all colliding geometries. The power factor τ is close to -(1)/(3) in central collisions, whereas it is -(2)/(3) for peripheral collisions suggesting stronger system size dependence at peripheral geometries. This also suggests that in the absence of momentum dependent interactions, Coulomb's interaction plays an exceedingly significant role. These results are further analyzed for nuclear dynamics at the balance point.

  11. Neutron Induced Reactions with the 17 Mev Facility at the Athens Tandem Accelerator NCSR 'Demokritos'

    NASA Astrophysics Data System (ADS)

    Vlastou, R.; Kalamara, A.; Serris, M.; Diakaki, M.; Kokkoris, M.; Paneta, V.; Axiotis, M.; Lagoyannis, A.

    In the 5.5 MV tandem T11/25 Accelerator Laboratory of NCSR "Demokritos" monoenergetic neutron beams have been produced in the energy range∼ 15-20 MeV using anew Ti-tritiated target of 373 GBq activity, by means of the 3H(d,n)4He reaction. The corresponding deuteron beam energies obtained from the accelerator, were in the 1.5-4.5MeV range.The maximum flux has been determined to be of the order of 106 n/cm2 s, implementing reference reactions. The 17.1MeV neutron beam has been used for the measurement of 197Au(n,2n) reaction cross section. Theoretical calculations have been performed via the statistical model code EMPIRE and compared to the experimental data of the present work and data from literature.

  12. Levels in 210Fr and the decay of a high-spin, multi-particle isomer

    NASA Astrophysics Data System (ADS)

    Margerin, V.; Lane, G. J.; Dracoulis, G. D.; Palalani, N.; Smith, M. L.

    2012-10-01

    The structure of 210Fr has been studied through the 197Au(18O, 5n)210Fr reaction. A high-spin isomeric state has been identified at ~4.4 MeV. It has a lifetime of 686(17) ns and decays by two γ-rays that are very likely to be either M2 or E3 multipolarity. The measured strengths in the case of E3 assignments are approximatively 8 and 21 W.u., respectively. These would be less enhanced than is observed in the decay from the high spin isomers in 209Fr and 211Fr that are believed to be from a related configuration. Possible configuration assignments are discussed.

  13. Determination of gold and platinum traces in biological materials as a part of a multi-element radiochemical activation analysis system.

    PubMed

    Tjioe, P S; Volkers, K J; Kroon, J J; de Goeij, J J; The, S K

    1984-01-01

    For the analysis of human tissues for traces of gold and platinum--being used as constituents of therapeutic agents--a radiochemical neutron activation method has been developed. The radiochemical separation involves the selective removal of radioactive gold--formed by the reaction 197Au (n, gamma)198Au and the reaction 198Pt (n, gamma) 199Pt ---- 199Au --as small metallic nuggets . The determination of gold and platinum is carried out as a part of an automated multi-element radiochemical separation scheme, allowing the determination of about 20 additional trace elements, and thus giving the possibility to study interelement relations. The analytical characteristics of the determination are evaluated. Gold and platinum levels measured in Bowen's Kale, NBS Bovine Liver and NBS Orchard Leaves are presented. Values are shown for gold, platinum, and 20 other trace elements in various healthy and cancerous tissues from patients treated with cis-platin. (Cis-Diamminedichloroplatinum II). PMID:6724783

  14. Study of heavy element structure with in-beam. cap alpha. /sup -/,. beta. /sup -/ and. gamma. -ray spectroscopy

    SciTech Connect

    Meyer, R.A.; Decman, D.J.; Henry, E.A.; Hoff, R.W.; Mann, L.G.; Struble, G.L.; Ussery, L.E.

    1984-05-10

    We describe our in-beam superconducting conversion electron spectrometer and its use in a (t,p) proton-conversion electron coincidence mode. Several examples of completed and on-going investigations are presented. These include: E0 strength from the /sup 238/U fission isomer; electromagnetic properties of the J/sup ..pi../ = 6/sup +/ and 8/sup +/ states of /sup 210/Pb; single particle and cluster states of /sup 213/Fr; the J/sup ..pi../ = 21/2/sup +/ isomer in /sup 197/Au and /sup 199/Au; and the cluster states of /sup 199/Au. Results of the study of odd-odd deformed /sup 244/Am are presented. The latter results performed using neutron-capture gamma-ray and conversion electron techniques are compared to recent developments in the modeling of deformed odd-odd nuclei. 23 refs., 10 figs., 1 tab.

  15. Semiclassical treatment of fusion and breakup processes of ^{6,8}He halo nuclei

    NASA Astrophysics Data System (ADS)

    Majeed, Fouad A.; Abdul-Hussien, Yousif A.

    2016-06-01

    A semiclassical approach has been used to study the effect of channel coupling on the calculations of the total fusion reaction cross section σ _{fus}, and the fusion barrier distribution D_{fus} for the systems 6He +^{238}U and 8He +^{197}Au. Since these systems invloves light exotic nuclei, breakup states channel play an important role that should be considered in the calculations. In semiclassical treatment, the relative motion between the projectile and target nuclei is approximated by a classical trajectory while the intrinsic dynamics is handled by time-dependent quantum mechanics. The calculations of the total fusion cross section σ _{fus}, and the fusion barrier distribution D_{fus} are compared with the full quantum mechanical calculations using the coupled-channels calculations with all order coupling using the computer code and with the available experimental data.

  16. Evaluation of Neutron Resonance Cross Section Data at GELINA

    NASA Astrophysics Data System (ADS)

    Schillebeeckx, P.; Becker, B.; Capote, R.; Emiliani, F.; Guber, K.; Heyse, J.; Kauwenberghs, K.; Kopecky, S.; Lampoudis, C.; Massimi, C.; Mondelaers, W.; Moxon, M.; Noguere, G.; Plompen, A. J. M.; Pronyaev, V.; Siegler, P.; Sirakov, I.; Trkov, A.; Volev, K.; Zerovnik, G.

    2014-05-01

    Over the last decade, the EC-JRC-IRMM, in collaboration with other institutes such as INRNE Sofia (BG), INFN Bologna (IT), ORNL (USA), CEA Cadarache (FR) and CEA Saclay (FR), has made an intense effort to improve the quality of neutron-induced cross section data in the resonance region. These improvements relate to both the infrastructure of the facility and the measurement setup, and the data reduction and analysis procedures. As a result total and reaction cross section data in the resonance region with uncertainties better than 0.5 % and 2 %, respectively, can be produced together with evaluated data files for both the resolved and unresolved resonance region. The methodology to produce full ENDF compatible files, including covariances, is illustrated by the production of resolved resonance parameter files for 241Am, Cd and W and an evaluation for 197Au in the unresolved resonance region.

  17. Plans for ENDF/B-VI

    SciTech Connect

    Pearlstein, S.; Dunford, C.L.

    1985-01-01

    Evaluation techniques are discussed for the Evaluated Nuclear Data File (ENDF/B). Adequacies and deficiencies of the program are summarized for criticality, fission ratios, capture-to-fission ratios, and shielding parameters. In addition, objectives for the future are presented. Evaluated data for incident particles, namely protons, will be included in the file. Evaluation improvements are planned for material of interest to the fusion and fission reactor programs. Cross section evaluations for /sup 238/U(n,f) and /sup 238/U(n,..gamma..) /sup 239/Pu(n,f), for example, will be added to the traditional list which includes: /sup 6/Li(n,t), /sup 10/B(n,..cap alpha..), /sup 197/Au(n,..gamma..) and /sup 235/U(n,f). 3 refs. (WRF)

  18. 63Ni (n ,γ ) cross sections measured with DANCE

    NASA Astrophysics Data System (ADS)

    Weigand, M.; Bredeweg, T. A.; Couture, A.; Göbel, K.; Heftrich, T.; Jandel, M.; Käppeler, F.; Lederer, C.; Kivel, N.; Korschinek, G.; Krtička, M.; O'Donnell, J. M.; Ostermöller, J.; Plag, R.; Reifarth, R.; Schumann, D.; Ullmann, J. L.; Wallner, A.

    2015-10-01

    The neutron capture cross section of the s -process branch nucleus 63Ni affects the abundances of other nuclei in its region, especially 63Cu and 64Zn. In order to determine the energy-dependent neutron capture cross section in the astrophysical energy region, an experiment at the Los Alamos National Laboratory has been performed using the calorimetric 4 π BaF2 array DANCE. The (n ,γ ) cross section of 63Ni has been determined relative to the well-known 197Au standard with uncertainties below 15%. Various 63Ni resonances have been identified based on the Q value. Furthermore, the s -process sensitivity of the new values was analyzed with the new network calculation tool NETZ.

  19. Competition between Coulomb and symmetry potential in semi-peripheral heavy ion collisions

    NASA Astrophysics Data System (ADS)

    Wu, Qianghua; Zhang, Yingxun; Xiao, Zhigang; Wang, Rensheng; Zhang, Yan; Li, Zhuxia; Wang, Ning; Showalter, R. H.

    2015-01-01

    The anisotropy of angular distributions of emitted nucleons and light charged particles for the asymmetric reaction system 40Ar+197Au , at b =6 fm and Ebeam=35 , 50, and 100 MeV /nucleon, is investigated by using the improved quantum molecular dynamics model. The competition between the symmetry potential and Coulomb potential shows large impacts on the nucleons and light charged particles emission in the projectile and target region. As a result of this competition, the angular distribution anisotropy of coalescence invariant neutron to proton yield ratio at forward regions shows sensitivity to the stiffness of symmetry energy as well as the value of neutron to proton yield ratio. This observable can be further checked against experimental data to understand the reaction mechanism and to extract information about the symmetry energy at subsaturation densities.

  20. 232Th(n,{gamma})233Th Thermal Reaction Cross-Section Measurement

    SciTech Connect

    Maidana, Nora L.; Vanin, Vito R.; Pascholati, Paulo R.; Helene, Otaviano; Castro, Ruy M.; Dias, Mauro S.; Koskinas, Marina F.

    2005-05-24

    The 232Th(n,{gamma})233Th thermal neutron-capture reaction cross section was measured using targets of {approx} 1.5 mg of high-purity metallic thorium irradiated in the IPEN IEA-R1m 5 MW pool research reactor. The 197Au(n,{gamma})198Au reaction was used to monitor the thermal and epithermal neutron fluxes in the irradiation position, which was found using the Westcott formalism. The residual gamma-ray activity was followed with an HPGe detector. The detector efficiency curve was fitted by the least-squares method applying covariance analysis to all uncertainties involved. The experimental result is {sigma}0 =7.20{+-}0.20 b, in agreement with previous published values.

  1. Measuring the cross sections of heavy-metal spallation induced by deuterons with energies of 2, 2.94, and 3.5 GeV per nucleon

    NASA Astrophysics Data System (ADS)

    Artyushenko, M. Yu.; Baldin, A. A.; Berlev, A. I.; Bukhal, O. V.; Voronko, V. A.; Gusak, K. V.; Zhuk, I. V.; Kudashkin, I. V.; Paraipan, M.; Potapenko, A. S.; Safronova, A. A.; Sotnikov, V. V.; Tyutyunnikov, S. I.

    2016-07-01

    The cross sections for the spallation of the heavy-metal nuclei 181Ta, 197Au, 207Pb, 209Bi, 232Th, and 238U induced by relativistic deuterons with energies of 2, 2.94, and 3.5 GeV per nucleon are measured using the deuteron beam from the Nuclotron accelerator of the JINR Laboratory of High Energy Physics in Dubna, Russia. The cross-section measurements employ a combined experimental technique involving the solidstate nuclear-track detectors and the activation gamma spectrometry. Adding our measurements to the database of experimental nuclear data will make it possible to test the computer codes used for selecting the parameters of the ADS-type facilities.

  2. Elastic scattering and total reaction cross section for the {sup 6}He+{sup 58}Ni system

    SciTech Connect

    Morcelle, V.; Lichtenthäler, R.; Lépine-Szily, A.; Guimarães, V.; Gasques, L.; Scarduelli, V.; Condori, R. Pampa; Leistenschneider, E.; Mendes Jr, D. R.; Faria, P. N. de; Pires, K. C. C.; Barioni, A.; Morais, M. C.; Shorto, J. M. B.; Zamora, J. C.

    2014-11-11

    Elastic scattering measurements of {sup 6}He + {sup 58}Ni system have been performed at the laboratory energy of 21.7 MeV. The {sup 6}He secondary beam was produced by a transfer reaction {sup 9}Be ({sup 7}Li, {sup 6}He) and impinged on {sup 58}Ni and {sup 197}Au targets, using the Radioactive Ion Beam (RIB) facility, RIBRAS, installed in the Pelletron Laboratory of the Institute of Physics of the University of São Paulo, Brazil. The elastic angular distribution was obtained in the angular range from 15° to 80° in the center of mass frame. Optical model calculations have been performed using a hybrid potential to fit the experimental data. The total reaction cross section was derived.

  3. Elastic scattering measurements for {sup 7}Be+{sup 27}Al system at RIBRAS facility

    SciTech Connect

    Morcelle, V.; Lichtenthaeler, R.; Morais, M. C.; Lepine-Szily, A.; Guimaraes, V.; Faria, P. N. de; Gasques, L.; Pires, K. C. C.; Condori, R. P.; Gomes, P. R. S.; Lubian, J.; Mendes, D. R. Jr.; Barioni, A.; Shorto, J. M. B.; Zamora, J. C.

    2013-05-06

    Elastic scattering angular distribution measurements of {sup 7}Be+{sup 27}Al system were performed at the laboratory energy of 15.6 MeV. The {sup 7}Be secondary beam was produced by the proton transfer reaction {sup 3}He({sup 6}Li,{sup 7}Be) and impinged on {sup 27}Al and {sup 197}Au targets, using the Radioactive Ion Beam (RIB) facility, RIBRAS. The elastic angular distribution was obtained within the angular range of 15{sup 0} - 80{sup 0} at the center of mass frame. Optical model calculations have been performed using the Woods- Saxon form factors and the Sao Paulo potential to fit the experimental data. The total reaction cross section was derived.

  4. Kilogramm und Mol: SI-Basiseinheiten für Masse und Stoffmenge

    NASA Astrophysics Data System (ADS)

    Becker, Peter; Gläser, Michael

    2001-11-01

    Das Kilogramm ist eine SI-Basiseinheit, die bislang nicht hinreichend genau auf Naturkonstanten zurückgeführt werden kann. Gegenwärtig gibt es verschiedene Vorschläge, dieses Problem zu lösen. Ein Vorschlag ist die Neudefinition des Kilogramm auf Basis atomarer Massen. An der Physikalisch-Technischen Bundesanstalt (PTB) wird dazu an zwei verschiedenen Verfahren geforscht. Beim ersten Verfahren werden Goldionen zu einer Referenzmasse akkumuliert, beim zweiten die Avogadro-Konstante an einem Silizium-Einkristall bestimmt. Beide Verfahren könnten eine genau bestimmbare Zahl von Atomen liefern, mit der das Kilogramm neu definiert werden könnte. Dies könnte eine Zahl von 197 Au, von 28 Si oder auch von 12 C-Atomen sein, auf der bereits die SI-Einheit der Stoffmenge des Mol basiert.

  5. Absence of entrance channel effects in fission fragment anisotropies of the {sup 215}Fr compound nucleus

    SciTech Connect

    Appannababu, S.; Mukherjee, S.; Singh, N. L.; Rath, P. K.; Kumar, G. Kiran; Thomas, R. G.; Santra, S.; Nayak, B. K.; Saxena, A.; Choudhury, R. K.; Golda, K. S.; Jhingan, A.; Kumar, R.; Sugathan, P.; Singh, Hardev

    2009-08-15

    Fission fragment angular distributions have been measured for the reactions {sup 11}B+{sup 204}Pb and {sup 18}O+{sup 197}Au, both leading to the same compound nucleus {sup 215}Fr at near barrier energies. The measured fission fragment anisotropies as a function of E{sub c.m.}/V{sub B} are found to be consistent with the predictions of the standard saddle point statistical model (SSPM) for both the systems, suggesting the absence of entrance channel effects on fission fragment anisotropies even though the entrance channel mass asymmetries for both these systems fall on either side of the Bussinaro-Gallone critical mass asymmetry. The consistency of the present results with SSPM predictions can be understood within the framework of the pre-equilibrium fission model where fission before K equilibration is severely inhibited by the high values of ratios of fission barrier height to nuclear temperature.

  6. High spin states and isomeric decays in doubly-odd 208Fr

    NASA Astrophysics Data System (ADS)

    Kanjilal, D.; Bhattacharya, S.; Goswami, A.; Kshetri, R.; Raut, R.; Saha, S.; Bhowmik, R. K.; Gehlot, J.; Muralithar, S.; Singh, R. P.; Jnaneswari, G.; Mukherjee, G.; Mukherjee, B.

    2010-10-01

    Neutron deficient isotopes of francium ( Z=87, N˜121-123) as excited nuclei were produced in the fusion-evaporation reaction: 197Au( 16O, xn) 213 - xFr at 100 MeV. The γ rays from the residues were observed through the high sensitivity Germanium Clover detector array INGA. The decay of the high spin states and the isomeric states of the doubly-odd 208Fr nuclei, identified from the known sequence of ground state transitions, were observed. The half-lives of the E=194(2) keV isomeric transition, known from earlier observations, was measured to be T=233(18) ns. A second isomeric transition at E=383(2) keV and T=33(7) ns was also found. The measured half-lives were compared with the corresponding single particle estimates, based on the level scheme obtained from the experiment.

  7. Magneto-optic trapping of {sup 210}Fr

    SciTech Connect

    Simsarian, J.E.; Ghosh, A.; Gwinner, G.; Orozco, L.A.; Sprouse, G.D.; Voytas, P.A.

    1996-05-01

    The alkali element francium has no stable isotopes and has eluded extensive study because sufficient quantities have not been available for detailed investigations. More than 1000 {sup 210}Fr atoms have now been contained in a magneto-optic trap. This number is sufficient to allow extensive studies of Fr atomic properties that are necessary input for future tests of fundamental interactions. The {sup 210}Fr ({ital T}{sub 1/2}=3.2 min) were created in the nuclear reaction {sup 197}Au({sup 18}O,5{ital n}){sup 210}Fr and were extracted from the target and injected into the trap. The ratio of the trap loading rate to the production rate in the target was 10{sup {minus}4}, which is 50 times larger than in previous experiments with {sup 79}Rb. {copyright} {ital 1996 The American Physical Society.}

  8. Silver and Gold NMR

    PubMed Central

    Zangger, Klaus

    1999-01-01

    Silver and gold, together with copper, form the transition metal group IB elements in the periodic table and possess very different nuclear magnetic resonance (NMR) spectroscopic properties. While there is only one gold isotope (197Au), which has a spin of 3/2 and therefore a quadrupole moment, silver occurs in two isotopic forms (109Ag and 109Au), both of which have a spin 1/2 and similar NMR spectroscopic properties. The unfavorable properties of gold have prevented its NMR spectroscopic investigation thus far. On the other hand, there are several reports of silver NMR. However, the low sensitivity of silver, combined with its long relaxation times have rendered the direct detection of silver possible only with concentrations greater than a few tenth molar. Reviewed here are the general limitations of silver NMR and some techniques to partially overcome these limitations, as well as a summary of currently available chemical shift and scalar coupling data on 109Ag. PMID:18475898

  9. Musett: A segmented Si array for Recoil-Decay-Tagging studies at VAMOS

    NASA Astrophysics Data System (ADS)

    Theisen, Ch.; Jeanneau, F.; Sulignano, B.; Druillole, F.; Ljungvall, J.; Paul, B.; Virique, E.; Baron, P.; Bervas, H.; Clément, E.; Delagnes, E.; Dijon, A.; Dossat, E.; Drouart, A.; Farget, F.; Flouzat, Ch.; De France, G.; Görgen, A.; Houarner, Ch.; Jacquot, B.; Korten, W.; Lebertre, G.; Lecornu, B.; Legeard, L.; Lermitage, A.; Lhenoret, S.; Marry, C.; Maugeais, C.; Menager, L.; Meunier, O.; Navin, A.; Nizery, F.; Obertelli, A.; Rauly, E.; Raine, B.; Rejmund, M.; Ropert, J.; Saillant, F.; Savajols, H.; Schmitt, Ch.; Tripon, M.; Wanlin, E.; Wittwer, G.

    2014-05-01

    A new segmented silicon-array called MUSETT has been built for the study of heavy elements using the Recoil-Decay-Tagging technique. MUSETT is located at the focal plane of the VAMOS spectrometer at GANIL and is used in conjunction with a γ-ray array at the target position. This paper describes the device, which consists of four 10×10 cm2 Si detectors and its associated front-end electronics based on highly integrated ASICs electronics. The triggerless readout electronics, the data acquisition and the analysis tools developed for its characterization are presented. This device was commissioned at GANIL with the EXOGAM γ-ray spectrometer using the fusion-evaporation reaction 197Au(22Ne,5n)214Ac. Additionally, the performance of the VAMOS Wien filter used during the in-beam commissioning is also reported.

  10. Shape manipulation of ion irradiated Ag nanoparticles embedded in lithium niobate.

    PubMed

    Wolf, Steffen; Rensberg, Jura; Johannes, Andreas; Thomae, Rainer; Smit, Frederick; Neveling, Retief; Moodley, Mathew; Bierschenk, Thomas; Rodriguez, Matias; Afra, Boshra; Bin Hasan, Shakeeb; Rockstuhl, Carsten; Ridgway, Mark; Bharuth-Ram, Krish; Ronning, Carsten

    2016-04-01

    Spherical silver nanoparticles were prepared by means of ion beam synthesis in lithium niobate. The embedded nanoparticles were then irradiated with energetic (84)Kr and (197)Au ions, resulting in different electronic energy losses between 8.1 and 27.5 keV nm(-1) in the top layer of the samples. Due to the high electronic energy losses of the irradiating ions, molten ion tracks are formed inside the lithium niobate in which the elongated Ag nanoparticles are formed. This process is strongly dependent on the initial particle size and leads to a broad aspect ratio distribution. Extinction spectra of the samples feature the extinction maximum with shoulders on either side. While the maximum is caused by numerous remaining spherical nanoparticles, the shoulders can be attributed to elongated particles. The latter could be verified by COMSOL simulations. The extinction spectra are thus a superposition of the spectra of all individual particles. PMID:26902734

  11. First tests of the applicability of γ-ray imaging for background discrimination in time-of-flight neutron capture measurements

    NASA Astrophysics Data System (ADS)

    Pérez Magán, D. L.; Caballero, L.; Domingo-Pardo, C.; Agramunt-Ros, J.; Albiol, F.; Casanovas, A.; González, A.; Guerrero, C.; Lerendegui-Marco, J.; Tarifeño-Saldivia, A.

    2016-07-01

    In this work we explore for the first time the applicability of using γ-ray imaging in neutron capture measurements to identify and suppress spatially localized background. For this aim, a pinhole gamma camera is assembled, tested and characterized in terms of energy and spatial performance. It consists of a monolithic CeBr3 scintillating crystal coupled to a position-sensitive photomultiplier and readout through an integrated circuit AMIC2GR. The pinhole collimator is a massive carven block of lead. A series of dedicated measurements with calibrated sources and with a neutron beam incident on a 197Au sample have been carried out at n_TOF, achieving an enhancement of a factor of two in the signal-to-background ratio when selecting only those events coming from the direction of the sample.

  12. Shape manipulation of ion irradiated Ag nanoparticles embedded in lithium niobate

    NASA Astrophysics Data System (ADS)

    Wolf, Steffen; Rensberg, Jura; Johannes, Andreas; Thomae, Rainer; Smit, Frederick; Neveling, Retief; Moodley, Mathew; Bierschenk, Thomas; Rodriguez, Matias; Afra, Boshra; Hasan, Shakeeb Bin; Rockstuhl, Carsten; Ridgway, Mark; Bharuth-Ram, Krish; Ronning, Carsten

    2016-04-01

    Spherical silver nanoparticles were prepared by means of ion beam synthesis in lithium niobate. The embedded nanoparticles were then irradiated with energetic 84Kr and 197Au ions, resulting in different electronic energy losses between 8.1 and 27.5 keV nm-1 in the top layer of the samples. Due to the high electronic energy losses of the irradiating ions, molten ion tracks are formed inside the lithium niobate in which the elongated Ag nanoparticles are formed. This process is strongly dependent on the initial particle size and leads to a broad aspect ratio distribution. Extinction spectra of the samples feature the extinction maximum with shoulders on either side. While the maximum is caused by numerous remaining spherical nanoparticles, the shoulders can be attributed to elongated particles. The latter could be verified by COMSOL simulations. The extinction spectra are thus a superposition of the spectra of all individual particles.

  13. Charged particles produced in neutron reactions on nuclei from beryllium to gold

    SciTech Connect

    Haight, R.C.

    1997-08-01

    Charged-particle production in reactions of neutrons with nuclei has been studied over the past several years with the spallation source of neutrons from 1 to 50 MeV at the Los Alamos Neutron Science Center (LANSCE). Target nuclides include 9Be, C, 27Al, Si, 56Fe, 59Co, 58,60Ni, 93Nb and 197Au. Proton, deuteron, triton, 3He and 4He emission spectra, angular distributions and production cross sections have been measured. Transitions from the compound nuclear reaction mechanism to precompound reactions are clearly seen in the data. The data are compared with data from the literature where available, with evaluated nuclear data libraries, and with calculations where the selection of the nuclear level density prescription is of great importance. Calculations normalized at En = 14 MeV can differ from the present data by a factor of 2 for neutron energies between 5 and 10 MeV.

  14. Experimental Study of Two-Alpha Emission from High-Lying Excited States of 17,18Ne

    NASA Astrophysics Data System (ADS)

    Xu, Xinxing; Lin, Chengjian; Jia, Huiming; Yang, Feng; Jia, Fei; Wu, Zhendong; Zhang, Shitao; Liu, Zuhua; Zhang, Huanqiao; Xu, Hushan; Sun, Zhiyu; Wang, Jiansong; Hu, Zhengguo; Wang, Meng; Chen, Ruofu; Zhang, Xueying; Li, Chen; Lei, Xiangguo; Xu, Zhiguo; Xiao, Guoqing

    2012-05-01

    The experiments of two-alpha emission from 17,18Ne excited levels were performed at the HIRFL-RIBLL facility of the Institute of Modern Physics, Lanzhou. The beams of 17Ne at the energy of 49.9 MeV/u and 18Ne at 51.8 MeV/u bombarded a 197Au target to populate excited states of 17,18Ne via Coulomb excitation. Complete kinematics measurements were achieved by the detectors of a silicon strip and CsI+PIN array. The experimental results combined with simple MC simulations show the characteristic of sequential two-alpha emission via 14O excited states for 18Ne. The results of two-alpha emission from 17Ne are preliminary and need further analyses.

  15. Global transverse energy distributions in Si+Al, Au at 14.6 A GeV/ c and Au+Au at 11.6 A GeV/ c

    NASA Astrophysics Data System (ADS)

    Ahle, L.; Akiba, Y.; Beavis, D.; Britt, H. C.; Budick, B.; Chasman, C.; Chen, Z.; Chi, C. Y.; Chu, Y. Y.; Cianciolo, V.; Cole, B. A.; Costales, J. B.; Crawford, H. J.; Cumming, J. B.; Debbe, R.; Engelage, J.; Fung, S. Y.; Gonin, M.; Gushue, S.; Hamagaki, H.; Hansen, O.; Hayano, R. S.; Hayashi, S.; Homma, S.; Kaneko, H.; Kang, J.; Kaufman, S.; Kehoe, W. L.; Kurita, K.; LeVine, M. J.; Miake, Y.; Morrison, D. P.; Moskowitz, B.; Nagamiya, S.; Namboodiri, M. N.; Nayak, T. K.; Olness, J.; Remsberg, L. P.; Rothschild, P.; Sangster, T. C.; Seto, R.; Shigaki, K.; Soltz, R.; Steadman, S. G.; Stephans, G. S. F.; Sung, T.; Tannenbaum, M. J.; Thomas, J.; Tonse, S.; Ueno, S.; van Dijk, J. H.; Videbaek, F.; Vossnack, O.; Wang, F. Q.; Wang, Y.; Wegner, H. E.; Woodruff, D. S.; Wu, Y. D.; Yagi, K.; Yang, X.; Zachary, D.; Zajc, W. A.; E-802 Collaboration

    1994-07-01

    Measurements of the global transverse energy distributions dσ/ dET and dET/ dη using the new AGS beam of 197Au at 11.6 A GeV/ c on a Au target, as well as a beam of 28Si at 14.6 A GeV/ c on Al and Au targets, are presented for a leadglass detector with acceptance 1.3 ≤ η ≤ 2.4 and 0 ≤ φ < 2 π. The dσ/ dET spectra are observed to have different shapes for the different systems and simple energy rescaling does not account for the projectile dependence. The Au+Au dσ/ dET spectrum is satisfactorily constructed from the upper edge of Si+Au by the geometric Wounded Projectile Nucleon Model after applying a correction for the beam energy.

  16. The detector system of the BigSol spectrometer at Texas A & M

    NASA Astrophysics Data System (ADS)

    Barbui, M.; Pesente, S.; Nebbia, G.; Fabris, D.; Lunardon, M.; Moretto, S.; Viesti, G.; Cinausero, M.; Prete, G.; Rizzi, V.; Bocci, F.; Chubarian, G.; Hagel, K.; Kowalski, S.; Materna, T.; Natowitz, J. B.; Souliotis, G.; Qin, L.; Wada, R.; Wang, J.; Majka, Z.; Wieloch, A.

    2007-12-01

    The detector system used at the first focus of the BigSol superconducting solenoid beam line at the Texas A & M superconducting cyclotron is presented. The system is composed of a position sensitive PPAC followed by an ionization chamber (IC) with a YAP(Ce) array in its back plane. The position sensitivity of the PPAC as well the energy resolution of the IC is investigated as a function of the counting rate. Pulse height, pulse height resolution and time resolution of the YAP(Ce) crystals are studied for a variety of heavy ion beams ranging from 20Ne to 197Au at energies from 15 AMeV to 40 AMeV. The pulse shape discrimination method using a Flash ADC is also explored, in order to identify decay products (alpha particles and electron/gamma) from the fragments implanted in the scintillator.

  17. Feeding of the 1 1/2- isomers in stable Ir and Au isotopes

    SciTech Connect

    Fotiadis, Nikolaos; Nelson, Ronald O; Devlin, Matthew; Holloway, Shannon T; Kawano, Toshihiko; Talou, Patrick; Chadwick, Mark B; Becker, John A; Garrett, Paul E

    2008-01-01

    Excited states were studied and absolute partial {gamma}-ray cross sections were measured using the ({eta}, {eta}'{gamma}) reaction in {sup 191}Ir, {sup 193}Ir and {sup 197}Au. A Compton-suppressed germanium-detector array (GEANIE) for {gamma}-ray spectroscopy and the broad-spectrum pulsed neutron source of the Los Alamos Neutron Science Center's WNR facility were used for the measurement. The energy of the incident neutrons was determined using the time-of-flight technique. Absolute partial {gamma}-ray cross sections were measured up to incident neutron energy of 20 MeV for several transitions feeding directly the 1 1/2- isomers and ground states in {sup 191}Ir, {sup 193}Ir and {sup 197}Au. The feeding of the 1 1/2- isomers, which originate from the odd proton occupying the h{sub 1 1/2} orbital, was found for the three targets to be very similar and increasing relative to the feeding of the corresponding ground state with increasing neutron energy up to E{sub n} {approx} 10 MeV. Above this neutron energy the opening of the (n, 2{sub n}) reaction channel strongly affects the population of the isomers and leads to a decrease of their relative population compared to the population of the ground states. The experimental results are compared with theoretical predictions from the GNASH reaction model calculation implementing a version of the spin distribution for the pre-equilibrium reaction piece with either a compound nucleus spin distribution (CN-GNASH) or a Feshbach-Kerman-Koonin (FKK-GNASH) quantum mechanical spin distribution. The effects of the spin cutoff parameter values on the population of states are examined. Evidence is presented that FKK-GNASH provides a description of the experimental data that mitigates the need for adjustment of the level density parameter to fit the data.

  18. Equilibrium and non-equilibrium emission of complex fragments

    SciTech Connect

    Bowman, D.R.

    1989-08-01

    Complex fragment emission (Z{gt}2) has been studied in the reactions of 50, 80, and 100 MeV/u {sup 139}La + {sup 12}C, and 80 MeV/u {sup 139}La + {sup 27}Al, {sup nat}Cu, and {sup 197}Au. Charge, angle, and energy distributions were measured inclusively and in coincidence with other complex fragments, and were used to extract the source rapidities, velocity distributions, and cross sections. The experimental emission velocity distributions, charge loss distributions, and cross sections have been compared with calculations based on statistical compound nucleus decay. The binary signature of the coincidence events and the sharpness of the velocity distributions illustrate the primarily 2-body nature of the {sup 139}La + {sup 12}C reaction mechanism between 50 and 100 MeV/u. The emission velocities, angular distributions, and absolute cross sections of fragments of 20{le}Z{le}35 at 50 MeV/u, 19{le}Z{le}28 at 80 MeV/u, and 17{le}Z{le}21 at 100 MeV/u indicate that these fragments arise solely from the binary decay of compound nuclei formed in incomplete fusion reactions in which the {sup 139}La projectile picks up about one-half of the {sup 12}C target. In the 80 MeV/u {sup 139}La + {sup 27}Al, {sup nat}Cu, and {sup 197}Au reactions, the disappearance of the binary signature in the total charge and velocity distributions suggests and increase in the complex fragment and light charged particle multiplicity with increasing target mass. As in the 80 and 100 MeV/u {sup 139}La + {sup 12}C reactions, the lighter complex fragments exhibit anisotropic angular distributions and cross sections that are too large to be explained exclusively by statistical emission. 143 refs., 67 figs.

  19. Covariances Obtained from an Evaluation of the Neutron Cross Section Standards

    SciTech Connect

    Carlson, A.D. Badikov, S.A.; Chen, Zhenpeng; Gai, E.; Hale, G.M.; Hambsch, F.-J.; Hofmann, H.M.; Kawano, T.; Larson, N.M.; Oh, S.Y.; Pronyaev, V.G.; Smith, D.L.; Tagesen, S.; Vonach, H.

    2008-12-15

    New measurements and an improved evaluation process were used to obtain a new evaluation of the neutron cross section standards. Efforts were made to include as much information as possible on the components of the data uncertainties that were then used to obtain the covariance matrices for the experimental data. Evaluations were produced from this process for the {sup 6}Li(n,t), {sup 10}B(n,{alpha}), {sup 10}B(n,{alpha}{sub 1}{gamma}), {sup 197}Au(n,{gamma}), {sup 235}U(n,f), and {sup 238}U(n,f) standard cross sections as well as the non-standard {sup 6}Li(n,n), {sup 10}B(n,n), {sup 238}U(n,{gamma}) and {sup 239}Pu(n,f) cross sections. There is a general increase in the cross sections for most of the new evaluations, by as much as about 5%, compared with the ENDF/B-VI results. Covariance data were obtained for the {sup 6}Li(n,t), {sup 6}Li(n,n), {sup 10}B(n,{alpha}), {sup 10}B(n,{alpha}{sub 1}{gamma}), {sup 10}B(n,n), {sup 197}Au(n,{gamma}), {sup 235}U(n,f), {sup 238}U(n,f), {sup 238}U(n,{gamma}) and {sup 239}Pu(n,f) reactions. Also an independent R-Matrix evaluation was produced for the H(n,n) standard cross-section, however, covariance data are not available for this reaction. The evaluations were used in the new ENDF/B-VII library.

  20. Studies of heavy ion reactions and transuranic nuclei. Progress report, August 1, 1983-August 31, 1984

    SciTech Connect

    Huizenga, J.R.; Schroeder, W.U.

    1984-08-01

    The status of the current understanding of the microscopic mechanisms operating in damped nuclear reactions is reviewed. Several experimental and conceptual problems of attempts to determine the nuclear interaction potential for distances inside the fusion barrier are discussed. An explanation of the unexpectedly large angular anisotropies of fragments from fission of heavy systems produced at large spins has been found in terms of the statistical scission model. In this model, the phase space available to the final deformed fission fragments governs the fission probability. Processes associated with incomplete linear-momentum transfer have been studied for 292-MeV /sup 20/Ne-induced fission with targets of /sup 165/Ho, /sup 181/Ta, /sup 197/Au, /sup 209/Bi, and /sup 238/U. Preequilibrium neutron emission has been studied in central and peripheral /sup 165/Ho + /sup 20/Ne and /sup 165/Ho + /sup 12/C collisions at bombarding energies between 11 and 25 MeV/nucleon. In preparation of kinematically complete coincidence experiments, a fast, position-sensitive avalanche detector with a large active area has been developed. The theoretical framework of the statistical scission model for fission has been reconsidered. Exclusive measurements were made of alpha particles emitted in the damped reaction /sup 165/Ho + /sup 56/Fe at E/sub Lab/ = 465 MeV. The data were interpreted with the aid of rather detailed Monte Carlo evaporation simulations. As part of an extensive coincidence study of equilibration mechanisms in damped reactions, inclusive measurements of projectile-like and fusion-fission-like fragments have been performed for the /sup 197/Au + /sup 51/V system at E/sub Lab/ = 447 MeV. The damped reaction features have been interpreted in terms of phenomenological reaction models. (WHK)

  1. Thermal neutron capture and resonance integral cross sections of 45Sc

    NASA Astrophysics Data System (ADS)

    Van Do, Nguyen; Duc Khue, Pham; Tien Thanh, Kim; Thi Hien, Nguyen; Kim, Guinyun; Kim, Kwangsoo; Shin, Sung-Gyun; Cho, Moo-Hyun; Lee, Manwoo

    2015-11-01

    The thermal neutron cross section (σ0) and resonance integral (I0) of the 45Sc(n,γ)46Sc reaction have been measured relative to that of the 197Au(n,γ)198Au reaction by means of the activation method. High-purity natural scandium and gold foils without and with a cadmium cover of 0.5 mm thickness were irradiated with moderated pulsed neutrons produced from the Pohang Neutron Facility (PNF). The induced activities in the activated foils were measured with a high purity germanium (HPGe) detector. In order to improve the accuracy of the experimental results the counting losses caused by the thermal (Gth) and resonance (Gepi) neutron self-shielding, the γ-ray attenuation (Fg) and the true γ-ray coincidence summing effects were made. In addition, the effect of non-ideal epithermal spectrum was also taken into account by determining the neutron spectrum shape factor (α). The thermal neutron cross-section and resonance integral of the 45Sc(n,γ)46Sc reaction have been determined relative to the reference values of the 197Au(n,γ)198Au reaction, with σo,Au = 98.65 ± 0.09 barn and Io,Au = 1550 ± 28 barn. The present thermal neutron cross section has been determined to be σo,Sc = 27.5 ± 0.8 barn. According to the definition of cadmium cut-off energy at 0.55 eV, the present resonance integral cross section has been determined to be Io,Sc = 12.4 ± 0.7 barn. The present results are compared with literature values and discussed.

  2. Extension of excitation functions up to 50 MeV for activation products in deuteron irradiations of Pr and Tm targets

    NASA Astrophysics Data System (ADS)

    Hermanne, A.; Tárkányi, F.; Takács, S.; Ditrói, F.

    2016-09-01

    Extension up to 50 MeV incident deuteron energy is presented for excitation functions of activation products formed in monoisotopic Tm (169Tm) and Pr (141Pr). By stacked foil irradiations direct and/or cumulative production of 140,139m,138Nd, 138mPr, 141,139,137m,135Ce on Pr and 166,169Yb, 166,167,168Tm on Tm targets were measured. Confirmation of earlier experimental results for all investigated radionuclides is found and the influence of the higher energy on thick target yields and batch production of medically relevant radionuclides (140Nd, 139Pr (as decay product of 139mNd), 166,169Yb, 167Tm) is discussed. A comparison of experimental values with TALYS1.6 code results (predicted values from TENDL-2015 on-line library) shows a better description of the (d,pxn) reactions than older ones.

  3. Electron Paramagnetic Resonance Study of Pr

    SciTech Connect

    Tezuka, Keitaro; Hinatsu, Yukio

    2001-01-01

    Electron paramagnetic resonance (EPR) spectra of tetravalent praseodymium ions doped in the cubic perovskite compound BaHfO{sub 3} have been measured at 4.2 K. A very large hyperfine interaction with the {sup 141}Pr nucleus was observed in the spectrum of Pr{sup 4+}/ BaHfO{sub 3}. The results were analyzed based on the weak field approximation, and the g value (|g|=0.619) and a hyperfine coupling constant (A=0.0589 cm{sup {minus}1}) were obtained. The measured g value is much smaller than |-10/7|, which indicates that the crystal field effect on the behavior of a 4f electron is large. These g and A values were compared with the EPR results for other f{sup 1} ions in an octahedral crystal field.

  4. Identification of new astatine isotopes using the gas-filled magnetic separator, SASSY

    SciTech Connect

    Yashita, S.

    1984-02-01

    A He-filled on-line mass separator system was built at the SuperHILAC and used to study the fusion products in the reaction /sup 56/Fe + /sup 141/Pr. The new neutron-deficient isotopes /sup 194/At and /sup 195/At were produced in this bombardment as three- and two- neutron-out products, respectively, and were identified by the ..cap alpha..-..cap alpha.. time-correlation technique. The measured ..cap alpha.. energies and half lives are 7.20 +- 0.02 MeV and 180 +- 80 msec for /sup 194/At, and 7.12 +- 0.02 MeV and 200 +- 100 msec for /sup 195/At. 66 references.

  5. Identification of new astatine isotopes using the gas-filled magnetic separator, Sassy

    SciTech Connect

    Yashita, S.

    1983-01-01

    A He-filled on-line separator system was built at the SuperHILAC and used to study the fusion products in the reaction /sup 56/Fe + /sup 141/Pr. The new neutron-deficient isotopes /sup 194/At and /sup 195/At were produced in this bombardment as three- and two-neutron-out products, respectively, and were identified by the ..cap alpha..-..cap alpha.. time-correlation technique. The measured ..cap alpha.. energies and half lives are 7.20 +/- 0.02 MeV and 180 +/- 80 msec for /sup 194/At, and 7.12 +/- 0.02 MeV and 200 +/- 100 msec for /sup 195/At.

  6. Neutron scattering studies in the actinide region. Progress report, August 1, 1991--July 31, 1994

    SciTech Connect

    Kegel, G.H.R.; Egan, J.J.

    1994-09-01

    During the period August 1, 1991 to July 31, 1994 the authors report progress on the following: (a) prompt fission neutron energy spectra for {sup 235}U and {sup 239}Pu; (b) two-parameter measurement of nuclear lifetimes; (c) `black` neutron detector; (d) data reduction techniques for neutron scattering experiments; (e) elastic and inelastic neutron scattering studies in {sup 197}Au; (f) elastic and inelastic neutron scattering studies in {sup 239}Pu; (g) neutron induced defects in silicon dioxide MOS structures; (h) response of a {sup 235}U fission chamber near reaction thresholds; (i) efficiency calibration of a liquid scintillation detector using the WNR facility at LAMPF; (j) prompt fission neutron energy spectrum measurements below the incident neutron energy; (k) multi-parameter data acquisition system; (l) accelerator improvements; (m) non-DOE supported research. Eight Ph.D. dissertations and two M.S. theses were completed during the report period. Publications consisted of 6 journal articles, 10 conference proceedings, and 19 abstracts of presentations at scientific meetings. One invited talk was given.

  7. Status of the International Neutron Cross-Section Standards File

    SciTech Connect

    Pronyaev, Vladimir G.; Badikov, Sergei A.; Gai, Evgeny V.; Chen Zhenpeng; Carlson, Allan D.; Hale, Gerald M.; Hambsch, Franz-Josef; Hofmann, Hartmut M.; Larson, Nancy M.; Smith, Donald L.; Oh, Soo-Youl; Tagesen, Siegfried; Vonach, Herbert

    2005-05-24

    A report is given of the progress achieved in an IAEA Co-ordinated Research Project (CRP) to improve the cross-section standards. The objectives of the CRP, started in 2002, were initially the understanding of the origin of the strong uncertainty reduction in R-matrix model fits and the improvement of the evaluation methodology. These aims were extended in 2003 to the preparation of new evaluations for the standard 6Li(n,t), 10B(n,{alpha}), 10B(n,{alpha}1), 197Au(n,{gamma}), 235U(n,f), and 238U(n,f) reactions. The methodology, codes, and experimental database developed by Poenitz and Hale for the ENDF/B-VI standards evaluation were taken as the basis for the new evaluation. The major results achieved by the CRP participants include the testing and intercomparison of a number of codes that can be used in the standards evaluation, updating the database of experimental results, analysis of the reasons leading to the strong uncertainty reduction in model fits, and a study of the bias in evaluated data caused by the Peelles's Pertinent Puzzle (PPP) effect, which has been widely discussed in the nuclear data community since the ENDF/B-VI standards evaluation was completed. Preliminary results of the new standards evaluation are shown. The use of the new 235U(n,f) cross section leads to better consistency in calculations of some important integral experiments.

  8. Three Stages of the NICA Accelerator Complex

    NASA Astrophysics Data System (ADS)

    Kekelidze, V. D.; Lednicky, R.; Matveev, V. A.; Meshkov, I. N.; Sorin, A. S.; Trubnikov, G. V.

    2016-01-01

    The Nuclotron-based Ion Collider fAcility (NICA) project is under development at JINR (Dubna). The general goals of the project are to provide colliding beams for experimental studies of both hot and dense strongly interacting baryonic matter and spin physics (in collisions of polarized protons and deuterons). The first program will require the running of heavy ion mode in the energy range of √sNN = 4÷11 GeV at an average luminosity of L = 1•1027 cm-2-s-1 for 197Au79 nuclei. This stage of the project will be preceded by fixed target experiments with the heavy ion beam to be extracted from the Nuclotron at kinetic energies up to 4.5 GeV/u. The polarized beam mode is proposed to be used in the energy range of √sNN = 12÷27 GeV (protons) at luminosities up to 1 • 1032 cm-2-s-1. This report contains a brief description of the facility scheme and characteristics in the heavy ion operation mode, the description of the MultiPurpose Detector (MPD), and characteristics of the reactions of the colliding ions, which will allow us to detect the mixed phase formation. The plans and status of the project development are presented.

  9. RESULTS FROM THE COMMISSIONING OF THE NSRL BEAM TRANSFER LINE AT BNL.

    SciTech Connect

    TSOUPAS,N.; BELLAVIA,S.; BONATI,R.; ET AL.

    2004-07-05

    The NASA SPACE RADIATION LABORATORY (NSRL) has been constructed and started operations at the Brookhaven National Laboratory in 2003. The NSRL facility will be used by NASA to perform radiation effect studies on materials and biological samples for the space program. The facility utilizes proton and heavy-ion beams of energies from 50 to 3000 MeVln which are accelerated by the AGS Booster synchrotron accelerator. To date, {sup 1}H, {sup 12}C, {sup 56}Fe, {sup 48}Ti, and {sup 197}Au ion beams of various magnetic rigidities have been extracted from the Booster, and transported by the NSRL beam transport line to the sample location which is located 100 m from the extraction point. The NSRL beam transport line has been designed to employ octupole magnetic elements which transform the normal (Gaussian) beam distribution at the location of the sample into a beam with rectangular cross section, and uniformly distributed over the sample. When using the octupole magnetic elements to obtain the uniform beam distribution on the sample, no beam-collimation is applied at any location along the NSRL beam transport line and the beam focusing on the sample is purely magnetic. The main subject of this paper will be the performance of the octupoles (third order optics) in obtaining uniform beam distributions at the target of the NSRL beam transport line.

  10. Studies of heavy-ion reactions and transuranic nuclei. Progress report, September 1, 1992--August 31, 1993

    SciTech Connect

    Schroeder, W.U.

    1993-08-01

    This report contain papers on the following topics: The Cold-Fusion Saga; Decay Patterns of Dysprosium Nuclei Produced in {sup 32}S + {sup 118,124}Sn Fusion Reactions; Unexpected Features of Reactions Between Very Heavy Ions at Intermediate Bombarding Energies; Correlations Between Neutrons and Charged Products from the Dissipative Reaction {sup 197}Au+{sup 208}Pb at E/A = 29 MeV; Dissipative Dynamics of Projectile-Like Fragment Production in the Reaction {sup 209}Bi+{sup 136}Xe at E/A = 28.2 MeV; Dynamical Production of Intermediate-Mass Fragments in Peripheral {sup 209}Bi+{sup 136}Xe Collisions at E{sub lab}/A = 28.2 MeV; The Rochester 960-Liter Neutron Multiplicity Meter; A Simple Pulse Processing Concept for a Low-Cost Pulse-Shape-Based Particle Identification; A One-Transistor Preamplifier for PMT Anode Signals; A Five-Channel Multistop TDC/Event Handler for the SuperBall Neutron Multiplicity Meter; Construction of the SuperBall -- a 16,000-Liter Neutron Detector for Calorimetric Studies of Intermediate-Energy Heavy-Ion Reactions; A Computer Code for Light Detection Efficiency Calculations for Photo-multipliers of a Neutron Detector; Evaluation of Gd-Loaded Liquid Scintillators for the SuperBall Neutron Calorimeter; and Measurement of the Interaction of Cosmic-Ray {mu}{sup {minus}} with a Muon Telescope.

  11. Neutron capture cross-section studies of Tellurium isotopes for neutrinoless double beta decay applications

    NASA Astrophysics Data System (ADS)

    Bhike, Megha; Tornow, Werner

    2014-09-01

    The CUORE detector at Gran Sasso, aimed at searching for neutrinoless double-beta decay of 130Te, employs an array of TeO2 bolometer modules. To understand and identify the contribution of muon and (α,n) induced neutrons to the CUORE background, fast neutron cature cross-section data of the tellurium isotopes 126Te, 128Te and 130Te have been measured with the activation method at eight different energies in the neutron energy range 0.5-7.5 MeV. Plastic pill boxes of diameter 1.6 cm and width 1 cm containing Te were irradiated with mono-energetic neutrons produced via the 3H(p,n)3He and 2H(d,n)3He reactions. The cross-sections were determined relative to the 197Au(n, γ)198Au and 115In(n,n')115m In standard cross sections. The activities of the products were measured using 60% lead-shielded HPGe detectors at TUNL's low background counting facility. The present results are compared with the evaluated data from TENDL-2012, ENDF/B-VII.1, JEFF-3.2 and JENDL-4.0, as well as with literature data.

  12. Three stages of the NICA accelerator complex

    NASA Astrophysics Data System (ADS)

    Kekelidze, V. D.; Lednicky, R.; Matveev, V. A.; Meshkov, I. N.; Sorin, A. S.; Trubnikov, G. V.

    2016-08-01

    The Nuclotron-based Ion Collider fAcility (NICA) project is under development at JINR (Dubna). The general goals of the project are to provide colliding beams for experimental studies of both hot and dense strongly interacting baryonic matter and spin physics (in collisions of polarized protons and deuterons). The first program will require the running of heavy-ion mode in the energy range of √{s_{NN}} = 4-11 GeV at luminosities up to L = 1\\cdot 10^{27} cm-2 s-1 for 197Au79 nuclei (see details in sect. 4). This stage of the project will be preceded by fixed target experiments with the heavy-ion beam to be extracted from the Nuclotron at kinetic energies up to 4.5 GeV/u. The polarized beam mode is proposed to be used in the energy range of √{s_{NN}} = 12-27 GeV (protons) at luminosities up to 1\\cdot 10^{32} cm-2 s-1. This report contains a brief description of the facility scheme and characteristics in the heavy-ion operation mode, the description of the MultiPurpose Detector (MPD), and characteristics of the reactions of the colliding ions, which will allow us to detect the mixed phase formation. The plans and status of the project development are presented.

  13. Validation of the MCNP computational model for neutron flux distribution with the neutron activation analysis measurement

    NASA Astrophysics Data System (ADS)

    Tiyapun, K.; Chimtin, M.; Munsorn, S.; Somchit, S.

    2015-05-01

    The objective of this work is to demonstrate the method for validating the predication of the calculation methods for neutron flux distribution in the irradiation tubes of TRIGA research reactor (TRR-1/M1) using the MCNP computer code model. The reaction rate using in the experiment includes 27Al(n, α)24Na and 197Au(n, γ)198Au reactions. Aluminium (99.9 wt%) and gold (0.1 wt%) foils and the gold foils covered with cadmium were irradiated in 9 locations in the core referred to as CT, C8, C12, F3, F12, F22, F29, G5, and G33. The experimental results were compared to the calculations performed using MCNP which consisted of the detailed geometrical model of the reactor core. The results from the experimental and calculated normalized reaction rates in the reactor core are in good agreement for both reactions showing that the material and geometrical properties of the reactor core are modelled very well. The results indicated that the difference between the experimental measurements and the calculation of the reactor core using the MCNP geometrical model was below 10%. In conclusion the MCNP computational model which was used to calculate the neutron flux and reaction rate distribution in the reactor core can be used for others reactor core parameters including neutron spectra calculation, dose rate calculation, power peaking factors calculation and optimization of research reactor utilization in the future with the confidence in the accuracy and reliability of the calculation.

  14. Thermal neutron capture cross sections for the 152Sm(n,γ) 153Sm and 154Sm(n,γ) 155Sm reactions at 0.0536 eV energy

    NASA Astrophysics Data System (ADS)

    Uddin, M. S.; Chowdhury, M. H.; Hossain, S. M.; Latif, Sk. A.; Islam, M. A.; Hafiz, M. A.; Mubin, S. H.; Zakaria, A. K. M.; Yunus, S. M.; Azharul Islam, S. M.

    2008-11-01

    The neutron capture cross sections for the 152Sm(n,γ) 153Sm and 154Sm(n,γ) 155Sm reactions at 0.0536 eV neutron energy were measured using an activation technique based on the TRIGA Mark-II research reactor, relative to the reference reaction 197Au(n,γ) 198Au. The activity was measured nondestructively using gamma-ray spectroscopy. Our measured values at this neutron energy are the first ones and are compared with 1/ v based evaluated cross sections reported in the ENDF/B-VII and JENDL-3.3 libraries. The measured value for the 152Sm(n,γ) 153Sm reaction is 0.28% lower than JENDL-3.3 and 0.48% higher than ENDF/B-VII. Our value for the production of 155Sm is about 3% and 2.3% higher than the evaluated value with ENDF/B-VII and JENDL-3.3 at 0.0536 eV, respectively.

  15. Measurement of neutron capture cross-section of the 71Ga(n, γ) 72Ga reaction at 0.0536 eV energy

    NASA Astrophysics Data System (ADS)

    Uddin, M. S.; Chowdhury, M. H.; Hossain, S. M.; Latif, Sk. A.; Hafiz, M. A.; Islam, M. A.; Zakaria, A. K. M.; Yunus, S. M.; Azharul Islam, S. M.

    2008-08-01

    The neutron capture cross-section for the 71Ga(n, γ) 72Ga reaction at 0.0536 eV energy was measured using activation technique based on TRIGA Mark-II research reactor. The 197Au(n, γ) 198Au monitor reaction was used to determine the effective neutron flux. Neutron absorption and γ-ray attenuation in gallium oxide pellet were corrected in determination of cross-section. The cross-section for the above reaction at 0.0536 eV amounts to 2.75 ± 0.14 b. As far as we know there are no experimental data available at our investigated energy. So far we are the first, who carried out experiment with 0.0536 eV neutrons for cross-section measurement. The present result is larger than that of JENDL-3.3, but consistent within the uncertainty range. The value of ENDF/B-VII is higher than this work. The result of this work will be useful to observe energy dependence of neutron capture cross-sections.

  16. Spectroscopy and high-spin structure of 210Fr: Isomerism and potential evidence for configuration mixing

    NASA Astrophysics Data System (ADS)

    Margerin, V.; Lane, G. J.; Dracoulis, G. D.; Palalani, N.; Smith, M. L.; Stuchbery, A. E.

    2016-06-01

    The structure of 210Fr has been established up to an excitation energy of ˜5.5 MeV and spins of ˜25 ℏ , via time-correlated γ -ray spectroscopy and using the 197Au(18O,5 n )210Fr reaction with pulsed beams at an energy of 97 MeV. A significantly different level scheme has been obtained compared to previous publications. Several isomers are reported here, including a Jπ=(23) +,τ =686 (9 ) -ns state at 4417 keV and a 10-, 29.8(11)-ns state at 1113 keV. The former isomer has been associated with the π (h9/2 3i13/2 2) ν (p1/2 -2f5/2 -1) configuration and decays via proposed E 3 transitions with strengths of 8.4(3) and 21.2(8) W.u. There are only very few known cases of a high-spin isomer decaying via two parallel E 3 transitions. Indeed, this is not seen in other Fr nuclei, and consequently these strengths differ from related decays in the neighboring isotopes. However, by examining the systematics of E 3 transitions in trans-lead nuclei, we suggest that the weaker of the two transitions decays to a mixed 20- state. Systematics of the 10- isomer are also discussed. Comparisons are made between the observed spectrum of states and those predicted from semiempirical shell-model calculations.

  17. Proton-helium correlation in 94 MeV/nucleon sup 16 O-induced reactions on Al, Ni, and Au targets

    SciTech Connect

    Badala, A.; Barbera, R.; Palmeri, A.; Pappalardo, G.S. ); Riggi, F. ); Bizard, G.; Durand, D.; Laville, J.L. )

    1992-04-01

    Azimuthal distributions of helium ions have been measured in coincidence with high-energy protons in reactions induced by {sup 16}O at 94 MeV/nucleon on {sup 27}Al, {sup 58}Ni, and {sup 197}Au. Helium ions have been detected in a large area multidetector. Protons have been observed at 90{degree}. Mean multiplicities of light charged particles (H and He) are found slightly dependent on the target mass. Strong azimuthal asymmetries whose intensity is larger for the Al target and vanishes with the increasing of the target mass are observed in the He distributions. Experimental data are discussed in the framework of the participant-spectator picture of a modified fireball model, taking into account intermediate energy corrections. In this framework the behavior of the azimuthal asymmetries, as a function of the target mass, indicates a strong final-state interaction between participant and spectator fragments. Such a result is found in agreement with interaction time predictions of a microscopical calculation based on the Boltzmann-Nordheim-Vlasov equation.

  18. Mass and Isospin Effects in Multifragmentation

    NASA Astrophysics Data System (ADS)

    Sfienti, C.; Adrich, P.; Aumann, T.; Bacri, C. O.; Barczyk, T.; Bassini, R.; Boiano, C.; Botvina, A. S.; Boudard, A.; Brzychczyk, J.; Chbihi, A.; Cibor, J.; Czech, B.; De Napoli, M.; Ducret, J.-E.; Emling, H.; Frankland, J.; Hellström, M.; Henzlova, D.; Kezzar, K.; Immé, G.; Iori, I.; Johansson, H.; Lafriakh, A.; Le Fèvre, A.; Le Gentil, E.; Leifels, Y.; Lynch, W. G.; Lühning, J.; Łukasik, J.; Lynen, U.; Majka, Z.; Mocko, M.; Müller, W. F. J.; Mykulyak, A.; Orth, H.; Otte, A. N.; Palit, R.; Pullia, A.; Raciti, G.; Rapisarda, E.; Sann, H.; Schwarz, C.; Simon, H.; Sokolov, A.; Sümmerer, K.; Trautmann, W.; Tsang, M. B.; Verde, G.; Volant, C.; Wallace, M.; Weick, H.; Wiechula, J.; Wieloch, A.; Zwieglinski, B.

    2005-03-01

    A systematic study of isospin effects in the breakup of projectile spectators at relativistic energies has been performed with the ALADiN spectrometer at the GSI laboratory (Darmstadt). Four different projectiles 197Au, 124La, 124Sn and 107Sn, all with an incident energy of 600 AMeV, have been used, thus allowing a study of various combinations of masses and N/Z ratios in the entrance channel. The measurement of the momentum vector and of the charge of all projectile fragments with Z > 1 entering the acceptance of the ALADiN magnet has been performed with the high efficiency and resolution achieved with the TP-MUSIC IV detector. The Rise and Fall behavior of the mean multiplicity of IMFs as a function of Zbound and its dependence on the isotopic composition has been determined for the studied systems. Other observables investigated so far include mean N/Z values of the emitted light fragments and neutron multiplicities. Qualitative agreement has been obtained between the observed gross properties and the predictions of the Statistical Multifragmentation Model.

  19. Constraining the high-density nuclear symmetry energy with the transverse-momentum-dependent elliptic flow

    NASA Astrophysics Data System (ADS)

    Wang, Yongjia; Guo, Chenchen; Li, Qingfeng; Zhang, Hongfei; Leifels, Y.; Trautmann, W.

    2014-04-01

    Within the newly updated version of the ultrarelativistic quantum molecular dynamics (UrQMD) model, the transverse-velocity dependence of the elliptic flow of free nucleons from Au197+Au197 collisions at the incident energy 400 MeV/nucleon is studied within different windows of the normalized c.m. rapidity y0. It is found that the elliptic flow difference v2n-v2p and ratio v2n/v2p of neutrons versus protons are sensitive to the density dependence of the symmetry energy, especially the ratio v2n/v2p at small transverse velocity in the intermediate rapidity intervals 0.4<|y0|<0.6. By comparing either transverse-momentum-dependent or integrated FOPI/LAND elliptic flow data of nucleons and hydrogen isotopes with calculations using various Skyrme interactions, all exhibiting similar values of isoscalar incompressibility but very different density dependences of the symmetry energy, a moderately soft to linear symmetry energy is extracted, in good agreement with previous UrQMD or Tübingen QMD model calculations but contrast with results obtained with π-/π+ yield ratios in the literature.

  20. Development of large area diamond detectors for time-of-flight measurements of relativistic heavy ions for the super-FRS

    NASA Astrophysics Data System (ADS)

    Schirru, F.; Nociforo, C.; Kiš, M.; Ciobanu, M.; Frühauf, J.; Kratz, A.; Kurz, N.; Szczepanczyk, B.; Träger, M.; Visinka, R.

    2016-06-01

    Time-of-flight (ToF) performances of large area diamond detectors based on polycrystalline samples of dimensions 20 mm  ×  20 mm and thickness of 0.3 mm are presented. The devices that feature segmented Cr/Au electrodes in a sandwich configuration were irradiated with a heavy ions 197Au beam of 1 GeV u‑1 showing, when mounted with a separation distance of 2 cm, a ToF resolution \\barσ of 37.5 ps averaged on 16 strip pairs. When ToF measurements were performed over a particle path of 30 m, a resolution σ of 45 ps was achieved. The detectors were mounted on high-vacuum compatible printed circuit boards (PCBs) with integrated processing electronics. This is the first time that ToF measurements have been performed using integrated electronics with such a large separation distance between the diamond detectors.

  1. Proof of the feasibility of coherent and incoherent schemes for pumping a gamma-ray laser. Annual technical progress report, 1 April 1988-31 March 1989

    SciTech Connect

    Collins, C.B.

    1989-06-01

    This report continues to focus upon the authors approach that is the nuclear analog to the ruby laser. It embodies the simplest concepts for a gamma-ray laser and, not surprisingly, the greatest rate of achievement in the quest for a subAngstrom laser continues in that direction. For ruby the identification and exploitation of a band-width funnel were the critical keys in the development of the first laser. There was a broad absorption band linked through efficient cascading to the narrow laser level. topics discussed include: Determination of Gateway States in {sup 197}Au with a Compton Gamma Ray; Determination of Photoexcitation Cross Sections for {sup 176}Lu (Gamma, Gamma) {sup 176}Lu(m) using A 6 MeV Bremsstrahlung Source; Accelerated Decay of 180a (m) and {sup 176}Lu in Stellar Interiors through (Gamma, Gamma) Reactions; Spectral Characterization of Intense, Short Duration Bremsstrahlung Pulses with Nuclear Photoactivation Techniques; The use of a Compton Spectrograph/Monochromator for the Photoactivation of Nuclei into Metastable States; Photoexcitation of Nuclear Isomers by (Gamma Gamma) Reactions through Relatively Unhindered Transitions Accessed with Bremsstrahlung from Medical Linear Accelerators; and Limits on Neutron Activation Interferences in Photoactivation Cross-Section Measurements in the 1.5-6 MeV Range.

  2. Strain fields around high-energy ion tracks in {alpha}-quartz

    SciTech Connect

    Follstaedt, D. M.; Norman, A. K.; Doyle, B. L.; McDaniel, F. D.

    2006-09-15

    Transmission electron microscopy has been used to image the tracks of high-energy {sup 197}Au{sup +26} (374 MeV) and {sup 127}I{sup +18} (241 MeV) ions incident in a nonchanneling direction through a prethinned specimen of hexagonal {alpha}-quartz (SiO{sub 2}). These ions have high electronic stopping powers in quartz, 24 and 19 keV/nm, respectively, which are sufficient to produce a disordered latent track. When the tracks are imaged with diffraction contrast using several different reciprocal lattice vectors, they exhibit a radial strain extending outward from their disordered centerline approximately 16 nm into the crystalline surroundings. The images are consistent with a radial strain field with cylindrical symmetry around the amorphous track, like that found in models developed to account for the lateral expansion of amorphous SiO{sub 2} films produced by irradiation with high-energy ions. These findings provide an experimental basis for increased confidence in such modeling.

  3. Time evolution of the luminosity of colliding heavy-ion beams in BNL Relativistic Heavy Ion Collider and CERN Large Hadron Collider

    SciTech Connect

    Bruce, R.; Blaskiewicz, M.; Jowett, J.M.; Fischer, W.

    2010-09-07

    We have studied the time evolution of the heavy ion luminosity and bunch intensities in the Relativistic Heavy Ion Collider (RHIC), at BNL, and in the Large Hadron Collider (LHC), at CERN. First, we present measurements from a large number of RHIC stores (from Run 7), colliding 100 GeV/nucleon {sup 197}Au{sup 79}+ beams without stochastic cooling. These are compared with two different calculation methods. The first is a simulation based on multi-particle tracking taking into account collisions, intrabeam scattering, radiation damping, and synchrotron and betatron motion. In the second, faster, method, a system of ordinary differential equations with terms describing the corresponding effects on emittances and bunch populations is solved numerically. Results of the tracking method agree very well with the RHIC data. With the faster method, significant discrepancies are found since the losses of particles diffusing out of the RF bucket due to intrabeam scattering are not modeled accurately enough. Finally, we use both methods to make predictions of the time evolution of the future {sup 208}Pb+{sup 82+} beams in the LHC at injection and collision energy. For this machine, the two methods agree well.

  4. Investigation of pion-nucleus interactions. Progress report, April 1, 1991--March 31, 1992

    SciTech Connect

    Moore, C.F.

    1992-09-01

    This report summarizes the work carried out by personnel from the University of Texas at Austin at the Los Alamos Clinton P. Anderson Meson Physics Facility (LAMPF). The research activities involved experiments done with the Energetic Pion Channel and Spectrometer (EPICS), the Low Energy Pion Channel (LEP), the Pion and Particle Physics Channel (P{sup 3}), the High Resolution Spectrometer (HRS), and planning a new experimental program associated with the new high-resolution Neutral Meson Spectrometer (NMS) at LAMPF. A brief overview of work supported by this grant is given followed by an account of the study of the double giant resonances in pion double charge exchange on {sup 51}V, {sup 115}In, and {sup 197}Au. This report contains a list of published papers and preprints, abstracts, and invited talks. These papers summarize experiments involving participants supported by this grant and indicate the work accomplished by these participants in this program of medium energy nuclear physics research. Lists of the most recent proposals on which we have participation at LAMPF, proposals which have been approved this past year to run as experiments, personnel who have participated in this research program are included. The research cited in this report is, in many cases, the collaborative effort of many groups associated with research at LAMPF.

  5. Investigation of pion-nucleus interactions. [295 MeV

    SciTech Connect

    Moore, C.F.

    1992-09-01

    This report summarizes the work carried out by personnel from the University of Texas at Austin at the Los Alamos Clinton P. Anderson Meson Physics Facility (LAMPF). The research activities involved experiments done with the Energetic Pion Channel and Spectrometer (EPICS), the Low Energy Pion Channel (LEP), the Pion and Particle Physics Channel (P[sup 3]), the High Resolution Spectrometer (HRS), and planning a new experimental program associated with the new high-resolution Neutral Meson Spectrometer (NMS) at LAMPF. A brief overview of work supported by this grant is given followed by an account of the study of the double giant resonances in pion double charge exchange on [sup 51]V, [sup 115]In, and [sup 197]Au. This report contains a list of published papers and preprints, abstracts, and invited talks. These papers summarize experiments involving participants supported by this grant and indicate the work accomplished by these participants in this program of medium energy nuclear physics research. Lists of the most recent proposals on which we have participation at LAMPF, proposals which have been approved this past year to run as experiments, personnel who have participated in this research program are included. The research cited in this report is, in many cases, the collaborative effort of many groups associated with research at LAMPF.

  6. Photoactivation of the p-nucleus 92Mo with bremsstrahlung at ELBE

    NASA Astrophysics Data System (ADS)

    Erhard, M.; Grosse, E.; Junghans, A. R.; Klug, J.; Nair, C.; Rusev, G.; Schilling, K. D.; Schwengner, R.; Wagner, A.

    2010-01-01

    In nuclear network calculations especially the p-nucleus 92Mo is frequently underproduced. Since experimental data of the photodisintegration of 92Mo so far do not exist, it was necessary to measure the reaction yields with the photoactivation method using the brems-strahlung facility ELBE at FZ Dresden-Rossendorf. Also the reaction 100Mo(γ,n) could be tested while irradiating Mo samples of natural composition. The photon fluence was measured with nuclear resonance fluorescence (NRF) of strong and well-known transitions in 11B. As a normalization standard the photoactivation reaction 197Au(γ,n) was used. For the 65 s half-life of 91mMo a fast pneumatic delivery was used. The photoactivation yields of the (γ,p) and (γ,n) reactions are compared to yield integrals of the bremsstrahlung spectral shape folded with the cross sections derived from Hauser-Feshbach nuclear model calculations using the TALYS program and cross sections from earlier experiments.

  7. Swift heavy ion-induced radiation damage in isotropic graphite studied by micro-indentation and in-situ electrical resistivity

    NASA Astrophysics Data System (ADS)

    Hubert, Christian; Voss, Kay Obbe; Bender, Markus; Kupka, Katharina; Romanenko, Anton; Severin, Daniel; Trautmann, Christina; Tomut, Marilena

    2015-12-01

    Due to its excellent thermo-physical properties and radiation hardness, isotropic graphite is presently the most promising material candidate for new high-power ion accelerators which will provide highest beam intensities and energies. Under these extreme conditions, specific accelerator components including production targets and beam protection modules are facing the risk of degradation due to radiation damage. Ion-beam induced damage effects were tested by irradiating polycrystalline, isotropic graphite samples at the UNILAC (GSI, Darmstadt) with 4.8 MeV per nucleon 132Xe, 150Sm, 197Au, and 238U ions applying fluences between 1 × 1011 and 1 × 1014 ions/cm2. The overall damage accumulation and its dependence on energy loss of the ions were studied by in situ 4-point resistivity measurements. With increasing fluence, the electric resistivity increases due to disordering of the graphitic structure. Irradiated samples were also analyzed off-line by means of micro-indentation in order to characterize mesoscale effects such as beam-induced hardening and stress fields within the specimen. With increasing fluence and energy loss, hardening becomes more pronounced.

  8. Neutron capture and fission cross section of /sup 243/Am in the energy range from 5 to 250 keV

    SciTech Connect

    Wisshak, K.; Kappeler, F.

    1983-11-01

    The neutron capture and subthreshold fission cross section of /sup 243/Am was measured in the energy range from 5 to 250 keV using /sup 197/Au and /sup 235/U as the respective standards. Neutrons were produced via the /sup 7/Li(p,n) and the T(p,n) reaction with the Karlsruhe 3-MV pulsed Van de Graaff accelerator. Capture events were detected by two Moxon-Rae detectors with graphite and bismuth graphite converters, respectively. Fission events were registered by an Ne-213 liquid scintillator with pulse-shape discriminator equipment. Flight paths as short as 50 to 70 mm were used to obtain an optimum signal-to-background ratio. After correction for the different efficiency of the individual converter materials, the capture cross section could be determined with a total uncertainty of 3 to 6%. The respective values for the fission cross section are 8 to 12%. The results are compared to predictions of recent evaluations, which in some cases are severely discrepant.

  9. Calculated gamma-ray spectra for keV neutron capture in /sup 240/Pu, /sup 242/Pu, and /sup 238/U

    SciTech Connect

    Reffo, G.; Fabbri, F.; Kappeler, F.; Wisshak, K.

    1983-03-01

    Capture gamma-ray spectra of /sup 240/Pu, /sup 242/Pu, and /sup 238/U were calculated in the framework of the spherical optical model and the statistical model. A consistent set of input parameters was determined from available experimental information or from model-guided systematics. The complete gamma-ray cascades were calculated considering all possible transitions up to multiplicity seven. All experimental information on level schemes and gamma-ray transition probabilities of the compound nuclei was explicitly included as input. The capture gamma-ray spectra were used to correct experimental data for the capture cross sections of /sup 240/Pu and /sup 242/Pu from a relative measurement using a Moxon-Rae detector with a graphite converter and with /sup 197/Au and /sup 238/U as standards. This correction is required to take into account that the detector efficiency is not exactly proportional to the gamma-ray energy. The resulting correction factors proved to be negligible for measurements relative to /sup 238/U; whereas, they are about 3% if gold is used as a standard.

  10. Ejection of fast electrons following the impact of 45 MeV/u 58Niq+ (q=19,28) on solid-foil targets

    NASA Astrophysics Data System (ADS)

    Lanzanò, G.; de Filippo, E.; Mahboub, D.; Rothard, H.; Aiello, S.; Anzalone, A.; Cavallaro, S.; Elanique, A.; Geraci, E.; Geraci, M.; Giustolisi, F.; Pagano, A.; Politi, G.

    2001-03-01

    We report absolute cross sections for binary encounter and convoy electron emission. Fast-electron velocity spectra were measured for atomic collisions induced by a 45 MeV/u 58Ni beam impinging on solid targets by means of the multidetector ARGOS in a large angular range (from 1.5° to 165°). Different conducting elemental targets (12C, 27Al, 58Ni and 64Ni, natAg, 197Au) and polystyrene were used. Characteristics of electrons with a velocity close to the beam velocity (convoy electrons) were found to be very sensitive to the incoming charge state of the projectile. Their yield increases with the target atomic number. The yield of binary encounter electrons with a velocity of almost twice the beam velocity at small ejection angles is roughly proportional to the area density of encountered target electrons. The velocity spectra centroids of these electrons are shifted towards lower velocities than predicted by simple two-body relativistic kinematics. Surprisingly, this effect seems to be mostly independent of target material and thickness. With increasing target atomic number, the high-energy tails of the spectra exhibit an unexpectedly large number of very fast electrons. A multiple-scattering mechanism involving multiple collision sequences of electrons between projectile and target atoms is invoked to explain this effect. The data also show evidence for an excess of fast electrons in the backward direction.

  11. Recent results on fast electron production induced by energetic heavy ions on thin solid targets

    NASA Astrophysics Data System (ADS)

    Lanzanò, G.; Anzalone, A.; Arena, N.; De Filippo, E.; Geraci, M.; Giustolisi, F.; Pagano, A.; Rothard, H.; Volant, C.

    2003-08-01

    In order to study the emission of energetic electrons induced by the impact of swift heavy ions on thin solid targets, we carried out a series of experiments at the Superconducting Cyclotron of the Catania Laboratori Nazionali del Sud (LNS) in November and December 2001. We bombarded solid thin targets, ranging from carbon to bismuth, with different ion beams at fixed velocity, i.e. ˜23 MeV/nucleon 197Au 36+, 58Ni 14+ and 12C 3+. Absolute velocity spectra were measured in a wide laboratory angular range, from 1.5° to 175°. At forward angles, besides the well-known convoy and binary encounter components with the beam velocity and two times the beam velocity respectively, we observe also a high velocity tail and an intermediate velocity component. At backward laboratory angles, the spectra remain complex, still presenting an energetic tail. These electron velocity spectra strongly depend on the beam and target atomic numbers. We suggest a Fermi-Shuttle (or multiscattering) mechanism and an in-flight-emission of projectile Auger electrons to explain some of the observed features in the velocity spectra.

  12. Formation of large target residues in intermediate energy nuclear collisions

    SciTech Connect

    Loveland, W.; Aleklett, K.; Sihver, L.; Xu, Z.; Seaborg, G.T.

    1987-04-01

    We have used radiochemical techniques to measure the yields, angular distributions and velocity spectra of the large (A/sub frag/ greater than or equal to 2/3 A/sub tgt/) target residues from the fragmentation of /sup 197/Au by intermediate energy /sup 12/C, /sup 20/Ne, /sup 32/S, /sup 40/Ar, /sup 84/Kr, and /sup 139/La projectiles. The fragment moving frame angular distributions are asymmetric for the lighter projectiles (C-Ar). The fragment velocity spectra are Maxwellian for the Kr induced reactions and non-Maxwellian for the reactions induced by the lighter ions. We interpret these results in terms of a change in the dominant fragment production mechanism(s) from one(s) involving a fast non-equilibrium process for the lighter ions to a slow, equilibrium process for Kr. Comparison of the measured yields and angular distributions with calculations made using a Boltzmann transport equation with appropriate modifications for Pauli blocking, etc., show excellent agreement between data and theory. 12 refs., 12 figs.

  13. Electron paramagnetic resonance in positively charged Au25 molecular nanoclusters.

    PubMed

    Akbari-Sharbaf, Arash; Hesari, Mahdi; Workentin, Mark S; Fanchini, Giovanni

    2013-01-14

    In this study, we investigated the unpaired electrons and singly occupied molecular orbitals (SOMO) of positively charged Au(25) molecular clusters using solid-state electron paramagnetic resonance (EPR). The EPR powder spectra of the positively charged (Au(25) (+)) and neutral (Au(25) (0)) species of Au(25) are discussed and compared. Our study demonstrates that Au(25) (+) is paramagnetic with a SOMO that is mostly localized about the central gold atom in the core of the molecule and possesses a strong p-type atomic character. The unpaired electron spin is demonstrated to strongly interact with the nuclear spins from other (197)Au nuclei in the core of Au(25) (+) molecules and the hyperfine tensor describing such interaction was extracted from the comparison of the EPR spectra with quantum mechanical simulations assuming an anisotropic structure of the core. Our simulations suggest that the core of Au(25) (+) molecular clusters is more distorted than in the corresponding neutral counterpart. They also confirm previous hypotheses suggesting that the icosahedral core of Au(25) (+) experiences contraction with decreasing temperature. PMID:23320681

  14. Isospin symmetry in the s d shell: Transition strengths in the neutron-deficient s d shell nucleus 33Ar

    NASA Astrophysics Data System (ADS)

    Wendt, A.; Taprogge, J.; Reiter, P.; Golubev, P.; Grawe, H.; Pietri, S.; Boutachkov, P.; Algora, A.; Ameil, F.; Bentley, M. A.; Blazhev, A.; Bloor, D.; Bondili, N. S.; Bowry, M.; Bracco, A.; Braun, N.; Camera, F.; Cederkäll, J.; Crespi, F.; de la Salle, A.; DiJulio, D.; Doornenbal, P.; Geibel, K.; Gellanki, J.; Gerl, J.; GrÈ©bosz, J.; Guastalla, G.; Habermann, T.; Hackstein, M.; Hoischen, R.; Jungclaus, A.; Merchán, E.; Million, B.; Morales, A.; Moschner, K.; Podolyák, Zs.; Pietralla, N.; Ralet, D.; Reese, M.; Rudolph, D.; Scruton, L.; Siebeck, B.; Warr, N.; Wieland, O.; Wollersheim, H. J.

    2014-11-01

    Reduced transition strengths of the deexciting transitions from the first two excited states in 33Ar were measured in a relativistic Coulomb excitation experiment at the GSI Helmholtz center. The radioactive ion beam was produced by fragmentation of a primary 36Ar beam on a 9Be target followed by the selection of the reaction product of interest via the GSI Fragment Separator. The 33Ar beam hit a secondary 197Au target with an energy of approximately 145 MeV/nucleon. An array of high-purity germanium cluster detectors and large-volume BaF2 scintillator detectors were employed for γ -ray spectroscopy at the secondary target position. The Lund-York-Cologne Calorimeter was used to track the outgoing ions and to identify the nuclear reaction channels. For the two lowest energy excited states of 33Ar the reduced transition strengths have been determined. With these first results the Tz=-3 /2 nucleus 33Ar is now, together with 21Na (Tz=-1 /2 ), the only neutron-deficient odd-A s d shell nucleus in which experimental transition strengths are available. The experimental values are compared to results of shell-model calculations which describe simultaneously mirror-energy differences and transition-strength values of mirror pairs in the s d shell in a consistent way.

  15. Stellar neutron capture cross section of the unstable s-process branching point {sup 151}Sm

    SciTech Connect

    Wisshak, K.; Voss, F.; Kaeppeler, F.; Krticka, M.; Raman, S.; Mengoni, A.; Gallino, R.

    2006-01-15

    The neutron capture cross sections of the radioactive isotope {sup 151}Sm and of natural samarium have been measured in the energy range from 3 keV to 225 keV at the Karlsruhe 3.7 MV Van de Graaff accelerator. Neutrons were produced via the {sup 7}Li(p,n){sup 7}Be reaction by bombarding metallic Li targets with a pulsed proton beam and capture events were registered with the Karlsruhe 4{pi} Barium Fluoride Detector. The cross sections were determined relative to the gold standard using a 206 mg sample of samarium oxide with 90% enrichment in {sup 151}Sm. Over most of the measured energy range uncertainties of {approx}2-3% could be achieved for the {sup 151}Sm/{sup 197}Au ratio. Maxwellian averaged neutron capture cross sections of {sup 151}Sm were calculated for thermal energies between kT = 8 keV and 100 keV with due consideration of the stellar enhancement factor and were found to be systematically larger than all previous theoretical predictions used in the analysis of the s-process branching at {sup 151}Sm. In the context of the branching analysis, an experimental determination of the stellar enhancement factor due to captures in thermally excited states is proposed, and the tentative determination of the p-process residual of {sup 152}Gd and a few other cases is discussed.

  16. Biological Effectiveness of Accelerated Particles for the Induction of Chromosome Damage Measured in Metaphase and Interphase Human Lymphocytes

    NASA Technical Reports Server (NTRS)

    George, Kerry; Durante, Marco; Willingham, Veronica; Wu, Honglu; Yang, Tracy C.; Cucinotta, Francis A.

    2003-01-01

    Chromosome aberrations were investigated in human lymphocytes after in vitro exposure to 1H-, 3He-, 12C-, 40Ar-, 28Si-, 56Fe-, or 197Au-ion beams, with LET ranging from approximately 0.4-1393 keV/microm in the dose range of 0.075-3 Gy. Dose-response curves for chromosome exchanges, measured at the first mitosis postirradiation using fluorescence in situ hybridization (FISH) with whole-chromosome probes, were fitted with linear or linear-quadratic functions. The relative biological effectiveness (RBE) was estimated from the initial slope of the dose-response curve for chromosomal damage with respect to low- or high-dose-rate gamma rays. Estimates of RBEmax values for mitotic spreads, which ranged from near 0.7 to 11.1 for total exchanges, increased with LET, reaching a maximum at about 150 keV/microm, and decreased with further increase in LET. RBEs for complex aberrations are undefined due to the lack of an initial slope for gamma rays. Additionally, the effect of mitotic delay on RBE values was investigated by measuring chromosome aberrations in interphase after chemically induced premature chromosome condensation (PCC), and values were up to threefold higher than for metaphase analysis.

  17. Measurement of 139La(n,γ) Cross Section

    NASA Astrophysics Data System (ADS)

    Terlizzi, R.; Abbondanno, U.; Aerts, G.; Álvarez, H.; Alvarez-Velarde, F.; Andriamonje, S.; Andrzejewski, J.; Assimakopoulos, P.; Audouin, L.; Badurek, G.; Baumann, P.; Bečvář, F.; Berthoumieux, E.; Calviño, F.; Cano-Ott, D.; Capote, R.; Carrillo de Albornoz, A.; Cennini, P.; Chepel, V.; Chiaveri, E.; Colonna, N.; Cortes, G.; Couture, A.; Cox, J.; Dahlfors, M.; David, S.; Dillmann, I.; Dolfini, R.; Domingo-Pardo, C.; Dridi, W.; Duran, I.; Eleftheriadis, C.; Embid-Segura, M.; Ferrant, L.; Ferrari, A.; Ferreira-Marques, R.; Fitzpatrick, L.; Frais-Koelbl, H.; Fujii, K.; Furman, W.; Gallino, R.; Goncalves, I.; Gonzalez-Romero, E.; Goverdovski, A.; Gramegna, F.; Griesmayer, E.; Guerrero, C.; Gunsing, F.; Haas, B.; Haight, R.; Heil, M.; Herrera-Martinez, A.; Igashira, M.; Isaev, S.; Jericha, E.; Kadi, Y.; Käppeler, F.; Karamanis, D.; Karadimos, D.; Kerveno, M.; Ketlerov, V.; Koehler, P.; Konovalov, V.; Kossionides, E.; Krtička, M.; Lamboudis, C.; Leeb, H.; Lindote, A.; Lopes, I.; Lozano, M.; Lukic, S.; Marganiec, J.; Marques, L.; Marrone, S.; Mastinu, P.; Mengoni, A.; Milazzo, P. M.; Moreau, C.; Mosconi, M.; Neves, F.; Oberhummer, H.; O'Brien, S.; Oshima, M.; Pancin, J.; Papachristodoulou, C.; Papadopoulos, C.; Paradela, C.; Patronis, N.; Pavlik, A.; Pavlopoulos, P.; Perrot, L.; Plag, R.; Plompen, A.; Plukis, A.; Poch, A.; Pretel, C.; Quesada, J.; Rauscher, T.; Reifarth, R.; Rosetti, M.; Rubbia, C.; Rudolf, G.; Rullhusen, P.; Salgado, J.; Sarchiapone, L.; Savvidis, I.; Stephan, C.; Tagliente, G.; Tain, J. L.; Tassan-Got, L.; Tavora, L.; Vannini, G.; Vaz, P.; Ventura, A.; Villamarin, D.; Vincente, M. C.; Vlachoudis, V.; Vlastou, R.; Voss, F.; Walter, S.; Wendler, H.; Wiescher, M.; Wisshak, K.

    2006-03-01

    We measured the neutron capture cross section of 139La relative to 197Au in the energy range of 0.6 eV to 9 keV at n_TOF, the neutron time-of-flight facility at CERN. After a description of the experimental apparatus, we discuss data analysis procedures. The data were fitted using R-matrix formalism to extract resonance parameters which, in turn, were used to calculate average level spacings D0 = 268 ± 22 eV and D1 < 250 eV, and neutron strength functions S0 = (0.79 ± 0.03)×10-4 and S1 = (0.73 ± 0.05)×10-4 for s- and p-wave resonances. The data also were used to determine Maxwellian-averaged neutron capture cross sections which, in turn, were used to calculate the 139La abundance synthesized in a stellar model of the main component of the s process.

  18. Actinide production from xenon bombardments of curium-248

    SciTech Connect

    Welch, R.B.

    1985-01-01

    Production cross sections for many actinide nuclides formed in the reaction of /sup 129/Xe and /sup 132/Xe with /sup 248/Cm at bombarding energies slightly above the coulomb barrier were determined using radiochemical techniques to isolate these products. These results are compared with cross sections from a /sup 136/Xe + /sup 248/Cm reaction at a similar energy. When compared to the reaction with /sup 136/Xe, the maxima in the production cross section distributions from the more neutron deficient projectiles are shifted to smaller mass numbers, and the total cross section increases for the production of elements with atomic numbers greater than that of the target, and decreases for lighter elements. These results can be explained by use of a potential energy surface (PES) which illustrates the effect of the available energy on the transfer of nucleons and describes the evolution of the di-nuclear complex, an essential feature of deep-inelastic reactions (DIR), during the interaction. The other principal reaction mechanism is the quasi-elastic transfer (QE). Analysis of data from a similar set of reactions, /sup 129/Xe, /sup 132/Xe, and /sup 136/Xe with /sup 197/Au, aids in explaining the features of the Xe + Cm product distributions, which are additionally affected by the depletion of actinide product yields due to deexcitation by fission. The PES is shown to be a useful tool to predict the general features of product distributions from heavy ion reactions.

  19. Spectroscopy and high-spin structure of {sup 209}Fr

    SciTech Connect

    Dracoulis, G. D.; Davidson, P. M.; Lane, G. J.; Kibedi, T.; Nieminen, P.; Watanabe, H.; Byrne, A. P.; Wilson, A. N.

    2009-05-15

    Excited states in {sup 209}Fr have been studied using the {sup 197}Au({sup 16}O,4n){sup 209}Fr reaction with pulsed beams and {gamma}-ray and electron spectroscopy. A comprehensive scheme has been established up to an excitation energy of about 6 MeV and spins of about 49/2({Dirac_h}/2{pi}). Several isomers have been identified including a J{sup {pi}}=25/2{sup +}, {tau}=48(3) ns state at 2130 keV and a 606(26) ns, 45/2{sup -} state at 4660 keV. The latter state decays via an enhanced E3 transition with a strength of 28.8(12) W.u. It can be identified with a similar isomer in the heavier odd isotopes {sup 211}Fr and {sup 213}Fr, arising from the maximal coupling of the five valence protons in the {pi}h{sub 9/2}{sup 3}i{sub 13/2}{sup 2} configuration. The systematics of the yrast states in the odd-A isotopes are discussed, including the presence of states arising from the main proton configurations coupled to the p{sub 1/2}, f{sub 5/2}, and i{sub 13/2} neutron holes. Shell-model configurations are assigned to many of the observed states. The isotopic assignment differs from earlier work, which is shown to be erroneous.

  20. Ion transport of Fr nuclear reaction products

    SciTech Connect

    Behr, J.A.; Cahn, S.B.; Dutta, S.B.

    1993-04-01

    Experiments planned for fundamental studies of radioactive atoms in magneto-optic traps require efficient deceleration and transport of nuclear reaction products to energies and locations where they can be trapped. The authors have built a low-energy ion transport system for Francium and other alkalis. A thick Au target is held on a W rod at 45{degrees} to the accelerator beam direction. The heavy-ion fusion reaction 115 MeV {sup 18}O + {sup 197}Au produces {sup 211,210,209}Fr recoil products which are stopped in the target. The target is heated to close to the melting point of Au to allow the Fr to diffuse to the surface, where it is ionized due to Au`s high work function, and is directly extracted by an electrode at 90{degrees} to the accelerator beam direction. The Fr is transported by electrostatic optics {approximately}1 m to a catcher viewed by an {alpha} detector: {ge}15% of the Fr produced in the target reaches the catcher. 2{times}10{sup 5} Fr/sec have been produced at the catcher, yielding at equilibrium a sample of 3x10{sup 7}Fr nuclei. This scheme physically decouples the target diffusion from the surface neutralization process, which can occur at a lower temperature more compatible with the neutral-atom trap.

  1. Francium sources at Laboratori Nazionali di Legnaro: Design and performance

    SciTech Connect

    Stancari, G.; Veronesi, S.; Corradi, L.; Atutov, S.N.; Calabrese, R.; Dainelli, A.; Mariotti, E.; Moi, L.; Sanguinetti, S.; Tomassetti, L.

    2006-03-15

    A facility for the production of radioactive francium is operating at the laboratories of the Istituto Nazionale di Fisica Nucleare (INFN) in Legnaro, Italy. The goal is to collect a cold sample of radioactive atoms in a magneto-optical trap for studies in atomic, nuclear, and particle physics. Production of francium is achieved via the fusion-evaporation reaction {sup 197}Au({sup 18}O,kn){sup 215-k}Fr generated by a {approx}100-MeV {sup 18}O{sup 6+} beam on a thick gold target. The production target is heated to {approx}1200 K and kept at a potential of +3 kV to enhance Fr diffusion and surface desorption. Average production rates are 0.7x10{sup 6} ions/s for {sup 210}Fr with a primary beam flux of 10{sup 12} particles/s, with peaks of 2x10{sup 6} ions/s. Details are given on the design and construction of the production targets and on the measurements that characterize their performance.

  2. Development of Thermal Ionizer for the Search of the Electron Electric Dipole Moment

    NASA Astrophysics Data System (ADS)

    Hayamizu, Tomohiro; Oikawa, Akihito; Takahashi, Toshiya; Yoshida, Hidetomo; Itoh, Masatoshi; Sakemi, Yasuhiro

    2009-10-01

    A non-zero Electric Dipole Moment (EDM) of an elementary particle means the violation of the time-reversal symmetry and the CP violation assuming the CPT invariance. The super symmetry model (SUSY) predicts the EDM large enough to be observed with the modern experimental technique. In alkali atoms, an electron EDM results in an atomic EDM enhanced by the factor ˜Z^3α^2, especially francium (Fr) has the largest enhancement factor ˜ 1150. However Fr is a radioactive atom with a finite life time, we need to establish the technique to produce over 10^7 atoms/sec, cool and collect them quickly into laser trap apparatus as a cold dense cloud of neutral atoms to measure the EDM accurately. Thermal Ionizer produce the high intensity Fr ion using a fusion reaction of ^18O+^197Au->^210Fr+5n with a primary beam energy E^18O ˜100 MeV. This ionizer consists of the Au target surrounded by the high temperature oven to stop the ion spreading out. Thanks to the small extraction electrode hole, we can realize the small emittance Fr beam, and the high transmission efficiency. We have achieved to produce over ˜10^4 atom/sec, and transport them along 3 meter without losing the Fr ions.

  3. Single-neutron states and the role of the νg9 / 2 orbital in 71Zn

    NASA Astrophysics Data System (ADS)

    Bottoni, Simone; ANL Collaboration; LBLN Collaboration; LLNL Collaboration; U. of Rochester Collaboration; U. of Maryland Collaboration

    2015-10-01

    The high-spin structure of 71Zn has been investigated at ATLAS by means of the deep inelastic reaction 48Ca+ 70Zn at 25% above the Coulomb barrier, using GRETINA and CHICO-2. In conjunction with GAMMASPHERE data from a similar reaction with a 70Zn beam on a thick 197Au target, a level scheme associated with the 3.96 h, 9/2+ isomer in 71Zn was delineated with the aim to achieve a better understanding of the nature of the neutron excitations close to N = 40. The level sequences built on the g9 / 2 neutron orbital all appear to be of single-particle character. The results will be presented and compared with shell-model calculations using modern effective interactions. This work is supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357 (ANL), DE-AC02-05CH11231 (LBNL, GRETINA), DE-AC52-07NA27344 (LLNL), and NSF.

  4. Electronic sputtering of vitreous SiO2: Experimental and modeling results

    NASA Astrophysics Data System (ADS)

    Toulemonde, M.; Assmann, W.; Trautmann, C.

    2016-07-01

    The irradiation of solids with swift heavy ions leads to pronounced surface and bulk effects controlled by the electronic energy loss of the projectiles. In contrast to the formation of ion tracks in bulk materials, the concomitant emission of atoms from the surface is much less investigated. Sputtering experiments with different ions (58Ni, 127I and 197Au) at energies around 1.2 MeV/u were performed on vitreous SiO2 (a-SiO2) in order to quantify the emission rates and compare them with data for crystalline SiO2 quartz. Stoichiometry of the sputtering process was verified by monitoring the thickness decreases of a thin SiO2 film deposited on a Si substrate. Angular distributions of the emitted atoms were measured by collecting sputtered atoms on arc-shaped Cu catcher foils. Subsequent analysis of the number of Si atoms deposited on the catcher foils was quantified by elastic recoil detection analysis providing differential as well as total sputtering yields. Compared to existing data for crystalline SiO2, the total sputtering yields for vitreous SiO2 are by a factor of about five larger. Differences in the sputtering rate and track formation characteristics between amorphous and crystalline SiO2 are discussed within the frame of the inelastic thermal spike model.

  5. Multiplicity dependence of two-pion correlations

    SciTech Connect

    Soltz, R.A.; E802 Collaboration

    1993-12-31

    Experiment E859 has measured two-pion correlations for 14.6 A{center_dot}GeV/c {sup 28}Si + Au and {sup 28}Si + Al systems as a function of total charged particle multiplicity. The data have been divided into three multiplicity regions for each system, and fits to two-dimensional Gaussian sources have been performed. The extracted source parameters R{sub l} and {tau} show little or no multiplicity dependence while the parameters R{sub t} and R show a slight dependence. Two-pion correlations were also measured for the 11.6 A{center_dot}GeV/c {sup 197}Au + Au system as part of experiment E866. The rms radius (R{sub rms}) for this system was found to be 7.03 {plus_minus} 0.53 fm, consistent with a scaling of R{sub rms} = 1.2A{sub p}{sup 1/3}, where A{sub p} is the number of projectile nucleons.

  6. The emittances and brightnesses of high-intensity negative ion sources

    SciTech Connect

    Alton, G.D.; McConnell, J.W.

    1987-01-01

    The emittances of high-intensity ion beams extracted from cesium sputter negative ion sources equipped with cylindrical and ellipsoidal solid tungsten and spiral-wound tantalum (General Ionex Corporation, Model 860), and cesium surface ionizers have been measured for several ion species, including /sup 12/C/sup -/, /sup 28/Si/sup -/, /sup 58/Ni/sup -/, and /sup 197/Au/sup -/. While certain sets of data from the ellipsoidal and cylindrical geometry ionizer sources suggest a moderate growth in emittance with increasing negative ion beam intensity I over the range of intensities investigated (5 less than or equal to 1 less than or equal to 60 ..mu..A) of perhaps 20%, not all data exhibit this dependence, especially those from the Model 860 source. As well, no evidence of an emittance dependence on ion mass of a monotonic nature was found. The emittances of ion beams at the 80% intensity level from the Model 860 source are found to be higher on the average by factors of 1.8 and 1.7, respectively, than those from sources equipped with ellipsoidal and cylindrical geometry cesium surface ionizers.

  7. Reaction rates of the 113In(γ,n)112mIn and 115In(γ,n)114mIn

    NASA Astrophysics Data System (ADS)

    Skakun, Ye; Semisalov, I.; Kasilov, V.; Popov, V.; Kochetov, S.; Maslyuk, V.; Mazur, V.; Parlag, O.; Gajnish, I.

    2016-01-01

    The integral yields of the 113In(γ,n)112mIn (Jπ=9/2+→Jπ=4+) and 115In(γ,n)114mIn (Jπ=9/2+→Jπ=5+) photonuclear reactions were measured in the bremsstrahlung end-point energy range from the respective thresholds up to 14 MeV by a conventional activation/decay technique using the 197Au(γ,n)196Au reaction cross sections as the standard for the absolute photon intensity determination. The metallic indium samples of the natural and enriched compositions were irradiated by the bremsstrahlung beams from thin tantalum converters of the electron linear accelerator of NSC KIPT (Kharkiv) and the microtron of IEP (Ughhorod). The integral reaction yields were determined from the activities of the nuclei-products measured by the high resolution γ-ray spectrometry technique with Ge(Li)- and HPGe-detectors. The reaction rates for the Planck spectrum of a thermal photon bath were derived for the ground state target nuclei and compared to the predictions of the statistical model of nuclear reactions.

  8. Status of NICA project

    SciTech Connect

    Meshkov, I. N.

    2012-05-15

    The project of Nuclotron-based Ion Collider fAcility NICA/MPD (+MultiPurpose Detector) under development at JINR (Dubna) is presented. The general goals of the project are providing of colliding beams for experimental studies of both hot and dense strongly interacting baryonicmatter and search for the mixed phase and critical endpoint and spin physics in collisions of polarized protons (deuterons). The first program requires providing of heavy-ion collisions in the energy range of {radical}s{sub NN} = 4 - 11 GeV at average luminosity of L = 1 Multiplication-Sign 10{sup 27} cm{sup -2} s{sup -1} for {sup 197}Au{sup 79+}. The polarized beams mode is proposed to be used in energy range of {radical}s = 12 - 27 GeV (protons) at luminosity of L {>=} 1 Multiplication-Sign 10{sup 30} cm{sup -2} s{sup -1}. The report contains description of the facility scheme and characteristics in heavy-ion operation mode, status and plans of the project development.

  9. Picosecond timing of high-energy heavy ions with semiconductor detectors

    NASA Astrophysics Data System (ADS)

    Eremin, Vladimir; Kiselev, Oleg; Egorov, Nicolai; Eremin, Igor; Tuboltsev, Yuri; Verbitskaya, Elena; Gorbatyuk, Andrei

    2015-10-01

    Construction of new accelerating facilities to investigate reactions with heavy ions requires upgrading of the Time-of-Flight (TOF) systems for on-line ion identification. The requested time resolution of the TOF system developed for Super FRagment Separator in the frame of the FAIR program at GSI, Germany, is in the range of tens of picoseconds, which can be realized by using planar silicon detectors. Such resolution will allow characterization of relativistic ions from Lithium to Uranium. However, fast timing of heavy ions with semiconductor detectors is expected to be limited by the so-called plasma effect due to a high concentration of electron-hole pairs in tracks. Here the results of the experiment with relativistic 197Au ions (the energy of 920 MeV per nucleon) obtained with Si detectors are described, which showed the TOF time resolution around 14 ps rms. The physical mechanism of charge collection from high-density penetrating tracks of relativistic heavy ions is considered and the analysis of timing characteristics is performed taking into account track polarization. Polarization is shown to have a strong influence on the formation of the leading edge of the detector current response generated by relativistic heavy ions, which allows us to explain the observed high time resolution.

  10. Optical Lattice Bose-Einstein Condensates and the dd Fusion - Iwamura Connection

    NASA Astrophysics Data System (ADS)

    Chubb, Talbot

    2003-03-01

    My conjecture: LENR dd fusion occurs in PdDx when a subset of the interstitial deuterons occupy tetrahedral sites in a PdDx crystallite. The tetrahedral deuterons(d's), which occupy shallow potential wells, behave as a superfluid, similar to ultracold Na atoms in shallow-well optical traps, as modeled by Jaksch et al.(D. Jaksch, et al, Phys. Rev. Lett., 81, 3108 (1998).) The tetrahedral d's form a deuteron (d) subsystem, which is neutralized by an electron subsystem containing an equal number of electrons. In the superfluid all the properties of each quasiparticle d are partitioned among N_s_i_te equivalent sites. The partitioning of the d point charge reduces the Coulomb self-repulsion within each quasiparticle pair, which causes wave function overlap at large N_s_i_t_e, allowing d-d fusion. Similarly, partitioning of the point charge of each single quasiparticle d reduces the Coulomb repulsion between it and an obstructing impurity atom, which causes wave function overlap between quasiparticle and atom at large N_s_i_t_e, allowing transmutation of the impurity atom. The Iwamura reaction(Y. Iwamura, et al, Japan J. of Appl. Physics, 41A, 4642 (2002).) is 4 ^2D^+_B_l_o_ch + 4 e^-_B_l_o_ch + ^1^3^3Cs arrow ^1^4^1Pr, with the reaction energy incoherently transferred to the lattice.

  11. Low lying electric dipole excitations in nuclei of the rare earth region

    SciTech Connect

    von Brentano, P.; Zilges, A.; Herzberg, R.D.; Zamfir, N.V.; Kneissl, U.; Heil, R.D.; Pitz, H.H.; Wesselborg, C.

    1992-10-01

    From many experiments with low energy photon scattering on deformed rare earth nuclei we have obtained detailed information about the distribution of electric dipole strength below 4 MeV. Apart from some weaker transitions between 2 and 4 MeV we observed one, and sometimes two, very strong El-groundstate transitions around 1.5 MeV in all examined nuclei. They arise from the de-excitation of the bandheads of the (J{sup {pi}},K)=(l{sup {minus}},0) and (J{sup {pi}},K)=(l{sup {minus}},1) octupole vibrational bands. It is shown that the decay branching ratios and the absolute transition strengths of these states can be reproduced rather well with an improved T(El)-operator in the sdf-Interacting Boson Model. Another class of octupole states has been investigated in the region of the semimagic nucleus {sup 142}Nd. Here a quintuplet of collective excitations around 3.5 MeV is expected due to the coupling of the 3{minus}-octupole vibration with the 2+-quadrupole vibration. We performed photon scattering experiments on the odd A neighboring nucleus {sup 141}Pr and found first evidence for the existence of 3{sup {minus}}{circle_times}2+{circle_times}particle-states.

  12. Short-lived isomers in 192Po and 194Po

    NASA Astrophysics Data System (ADS)

    Andel, B.; Andreyev, A. N.; Antalic, S.; Heßberger, F. P.; Ackermann, D.; Hofmann, S.; Huyse, M.; Kalaninová, Z.; Kindler, B.; Kojouharov, I.; Kuusiniemi, P.; Lommel, B.; Nishio, K.; Page, R. D.; Sulignano, B.; Van Duppen, P.

    2016-06-01

    Isomeric states in 194Po and 192Po were studied at the velocity filter SHIP. The isotopes were produced in the fusion-evaporation reactions 141Pr(56Fe, p 2 n )194Po and 144Sm(51V, p 2 n )192Po . Several new γ -ray transitions were attributed to the isomers and γ -γ coincidences for both isomers were studied for the first time. The 459-keV transition earlier, tentatively proposed as de-exciting the isomeric level in 194Po, was replaced by a new 248-keV transition, and the spin of this isomer was reassigned from (11-) to (10-). The de-excitation of the (11-) isomeric level in 192Po by the 154-keV transition was confirmed and a parallel de-excitation by a 733-keV (E 3 ) transition to (8+) level of the ground-state band was suggested. Moreover, side feeding to the (4+) level of the ground-state band was proposed. The paper also discusses strengths of transitions de-exciting 11- isomers in neighboring Po and Pb isotopes.

  13. {alpha} decay studies of very neutron-deficient francium and radium isotopes

    SciTech Connect

    Uusitalo, J.; Leino, M.; Enqvist, T.; Grahn, T.; Greenlees, P.T.; Jones, P.; Julin, R.; Juutinen, S.; Keenan, A.; Kettunen, H.; Koivisto, H.; Kuusiniemi, P.; Leppaenen, A.-P.; Nieminen, P.; Pakarinen, J.; Rahkila, P.; Scholey, C.; Eskola, K.

    2005-02-01

    Very neutron-deficient francium and radium isotopes have been produced in fusion evaporation reactions using {sup 63}Cu and {sup 65}Cu ions on {sup 141}Pr targets and {sup 36}Ar ions on {sup 170}Yb targets. The gas-filled recoil separator RITU was employed to collect the fusion products and to separate them from the scattered beam. The activities were implanted into a position-sensitive silicon detector after passing through a gas-counter system. The isotopes were identified using spatial and time correlations between the implants and decays. Two new {alpha} decaying radium isotopes, {sup 201}Ra and {sup 202}Ra, were identified. The {alpha} decay energy and half-life of {sup 203}Ra were measured with improved precision. The {alpha} decay properties measured for the francium isotopes {sup 201}Fr,{sup 202}Fr,{sup 203}Fr, and {sup 204}Fr were confirmed, in many cases with improved precision. For the first time, a ({pi}s{sub 1/2}{sup -1})1/2{sup +} proton intruder state was identified in francium isotopes, namely in {sup 201}Fr and tentatively in {sup 203}Fr. The measured decay properties for the neutron-deficient odd-mass Fr isotopes suggest an onset of substantial deformation at N=112.

  14. α-decay studies of the francium isotopes 198Fr and 199Fr

    NASA Astrophysics Data System (ADS)

    Uusitalo, J.; Sarén, J.; Juutinen, S.; Leino, M.; Eeckhaudt, S.; Grahn, T.; Greenlees, P. T.; Jakobsson, U.; Jones, P.; Julin, R.; Ketelhut, S.; Leppänen, A.-P.; Nyman, M.; Pakarinen, J.; Rahkila, P.; Scholey, C.; Semchenkov, A.; Sorri, J.; Steer, A.; Venhart, M.

    2013-06-01

    Very neutron deficient francium isotopes have been produced in fusion evaporation reactions using 60Ni ions on 141Pr targets. The gas-filled recoil separator RITU was employed to collect the fusion products and to separate them from the scattered beam. The activities were implanted into a position sensitive silicon detector after passing through a gas-counter system. The isotopes were identified using spatial and time correlations between the implants and the decays. Two α-particle activities, with Eα=7613(15) keV and T1/2 = (15-5+12) ms and Eα=7684(15) keV and T1/2 = (16-5+13) ms were identified in the new isotope 198Fr. In addition, the half-life and α-particle energy of 199Fr were measured with improved precision. The measured decay properties deduced for 199Fr and 198Fr suggest that there is an onset of ground-state deformation at N=112 in the Fr isotopes.

  15. α decay of the very neutron-deficient isotopes 197-199Fr

    NASA Astrophysics Data System (ADS)

    Kalaninová, Z.; Andreyev, A. N.; Antalic, S.; Heßberger, F. P.; Ackermann, D.; Andel, B.; Drummond, M. C.; Hofmann, S.; Huyse, M.; Kindler, B.; Lane, J. F. W.; Liberati, V.; Lommel, B.; Page, R. D.; Rapisarda, E.; Sandhu, K.; Šáro, Š.; Thornthwaite, A.; Van Duppen, P.

    2013-04-01

    Decay properties of the very neutron-deficient isotopes 197-199Fr were studied at the velocity filter Separator for Heavy Ion reaction Products (SHIP) at GSI in Darmstadt. The isotopes were produced in the 2n-4n evaporation channels of the fusion-evaporation reaction 60Ni+141Pr → 201Fr*. Improved α-decay properties of 199Fr were determined and the possible existence of two α-decaying states in this nucleus is discussed. For the isotope 198Fr a broad α-decay energy distribution was detected in the range of (7470-7930) keV and two α-decaying states were observed with half-lives of 1.1(7) and 15(3) ms. The new isotope 197Fr was identified based on the observation of one α-decay chain yielding Eα=7728(15) keV and T1/2=0.6-0.3+3.0 ms. The systematics of reduced α-decay widths are presented for neutron-deficient francium, radon, and astatine isotopes.

  16. {alpha} decay of {sup 194}At

    SciTech Connect

    Andreyev, A. N.; Antalic, S.; Streicher, B.; Saro, S.; Venhart, M.; Ackermann, D.; Heinz, S.; Hessberger, F. P.; Kojouharov, I.; Kindler, B.; Lommel, B.; Mann, R.; Sulignano, B.; Bianco, L.; Page, R. D.; Sapple, P.; Thomson, J.; Franchoo, S.; Hofmann, S.; Huyse, M.

    2009-06-15

    Detailed {alpha}-decay studies of the neutron-deficient isotope {sup 194}At have been performed in the complete fusion reaction {sup 56}Fe+{sup 141}Pr{yields}{sup 194}At+3n at the velocity filter SHIP. Two {alpha}-decaying isomeric states with half-lives of T{sub 1/2}({sup 194}At{sup m1})=310(8) ms and T{sub 1/2}({sup 194}At{sup m2})=253(10) ms were identified in this nucleus. Their complex decays to the states in the daughter nucleus {sup 190}Bi are discussed in the article. We propose that similar to the case of the neighboring {sup 191,192,193,195}At isotopes, the oblate-deformed configurations based on the proton 1/2{sup +}[440] and/or 7/2{sup -}[514] Nilsson orbitals become important in {sup 194}At. A new isomeric state with the half-life of 175(8) ns was observed in {sup 190}Bi.

  17. Rapid and precise determination of natural carbonate rare earth elements in femtogram quantities by ICP-SF-MS

    NASA Astrophysics Data System (ADS)

    Wu, C.; Liu, Y.; Shen, C.

    2011-12-01

    A rapid and precise technique for measuring of femtogram quantity rare earth elements (REE) levels in natural carbonate samples by ICP-SF-MS has been developed at the Department of Geosciences, National Taiwan University. REE/Ca ratios are calculated directly from the intensities of the ion beams of 46Ca, 139La, 140Ce, 141Pr, 146Nd, 147Sm, 153Eu, 160Gd, 159Tb, 163Dy, 165Ho, 166Er, 169Tm, 172Yb, and 175Lu using external matrix-matched synthetic standards to correct for instrumental ratio drifting and mass discrimination. A routine measurement time of 3 minutes is typical for one sample containing 20-40-ppm [Ca]. Replicate measurements made on natural coral and foraminiferal samples with REE/Ca ratios of 2-242 nmol/mol show external precisions of 1.9-6.5% (2RSD) can be achieved with only 10-1000 femtogram REEs in 10-20 μg carbonate consumed. The key advantages of this established technique are (1) to provide a possibility of directly analyzing REE isotopic composition in femtogram quantities without chemical separation steps, and (2) to potentially offer high precision and high temporal resolution REE records for diverse carbonates, such as corals, foraminifera, sclerosponges, tufa, and speleothems.

  18. Competition between the compound and the pre-compound emission processes in α-induced reactions at near astrophysical energy to well above it

    NASA Astrophysics Data System (ADS)

    Sharma, Manoj Kumar; Sharma, Vijay Raj; Yadav, Abhiskek; Singh, Pushpendra P.; Singh, B. P.; Prasad, R.

    2016-04-01

    The study of pre-compound emission in α-induced reactions, particularly at the low incident energies, is of considerable interest as the pre-compound emission is more likely to occur at higher energies. With a view to study the competition between the compound and the pre-compound emission processes in α-induced reactions at different energies and with different targets, a systematics for neutron emission channels in targets 51V, 55Mn, 93Nb, 121, 123Sb and 141Pr at energy ranging from astrophysical interest to well above it, has been developed. The off-line γ-ray-spectrometry based activation technique has been adopted to measure the excitation functions. The experimental excitation functions have been analysed within the framework of the compound nucleus mechanism based on the Weisskopf-Ewing model and the pre-compound emission calculations based on the geometry dependent hybrid model. The analysis of the data shows that experimental excitation functions could be reproduced only when the pre-compound emission, simulated theoretically, is taken into account. The strength of pre-compound emission process for each system has been obtained by deducing the pre-compound fraction. Analysis of data indicates that in α-induced reactions, the pre-compound emission process plays an important role, particularly at the low incident energies, where the pure compound nucleus process is likely to dominate.

  19. Measurement of the 115In(n,γ)116 m In reaction cross-section at the neutron energies of 1.12, 2.12, 3.12 and 4.12 MeV

    NASA Astrophysics Data System (ADS)

    Lawriniang, Bioletty Mary; Badwar, Sylvia; Ghosh, Reetuparna; Jyrwa, Betylda; Vansola, Vibha; Naik, Haladhara; Goswami, Ashok; Naik, Yeshwant; Datrik, Chandra Shekhar; Gupta, Amit Kumar; Singh, Vijay Pal; Pol, Sudir Shibaji; Subramanyam, Nagaraju Balabenkata; Agarwal, Arun; Singh, Pitambar

    2015-08-01

    The 115In(n,γ)116 m In reaction cross section at neutron energies of 1.12, 2.12, 3.12 and 4.12 MeV was determined by using an activation and off-line γ-ray spectrometric technique. The monoenergetic neutron energies of 1.12 - 4.12 MeV were generated from the 7Li(p,n) reaction by using proton beam with energies of 3 and 4 MeV from the folded tandem ion beam accelerator (FOTIA) at Bhabha Atomic Research Centre (BARC) and with energies of 5 and 6 MeV from the Pelletron facility at Tata Institute of Fundamental Research (TIFR), Mumbai. The 197Au(n,γ)198Au reaction cross-section was used as the neutron flux monitor.The 115In(n,γ)116 m In reaction cross section at neutron energies of 1.12, 2.12, 3.12 and 4.12 MeV was determined by using an activation and off-line γ-ray spectrometric technique. The monoenergetic neutron energies of 1.12 - 4.12 MeV were generated from the 7Li(p,n) reaction by using proton beam with energies of 3 and 4 MeV from the folded tandem ion beam accelerator (FOTIA) at Bhabha Atomic Research Centre (BARC) and with energies of 5 and 6 MeV from the Pelletron facility at Tata Institute of Fundamental Research (TIFR), Mumbai. The 197Au(n,γ)198 Au reaction cross-section was used as the neutron flux monitor. The 115In(n,γ)116 m In reaction cross-sections at neutron energies of 1.12 - 4.12 MeV were compared with the literature data and were found to be in good agreement with one set of data, but not with others. The 115In(n,γ)116 m In cross-section was also calculated theoretically by using the computer code TALYS 1.6 and was found to be slightly lower than the experimental data from the present work and the literature.)198Au reaction cross-section was used as the neutron flux monitor. The 115In(n,γ)116 m In reaction cross-sections at neutron energies of 1.12 - 4.12 MeV were compared with the literature data and were found to be in good agreement with one set of data, but not with others. The 115In(n,γ)116 m In cross-section was also calculated

  20. Characterization of Neutron and Gamma Dose in the Irradiation Cell of Texas A and M University Research Reactor

    SciTech Connect

    Vasudevan, Latha; Reece, Warren D.; Chirayath, Sunil S.; Aghara, Sukesh

    2011-07-01

    The Monte Carlo N-Particle (MCNP) code was used to develop a three dimensional computational model of the Texas A and M University Nuclear Science Center Reactor (NSCR) operating against the irradiation (dry cell) at steady state thermal power of 1 MW. The geometry of the NSCR core and the dry cell were modeled in detail. NSCR is used for a wide variety of experiments that utilizes the dry cell for neutron as well as gamma irradiation of samples. Information on the neutron and gamma radiation environment inside the dry cell is required to facilitate irradiation of samples. This paper presents the computed neutron flux, neutron and gamma dose rate, and foil reaction rates in the dry cell, obtained through MCNP5 simulations of the NSCR core. The neutron flux was measured using foil activation method and the reaction rates obtained from {sup 197}Au(n,{gamma}){sup 198}Au and {sup 54}Fe(n,p){sup 54}Mn were compared with the model and they showed agreement within {approx} 20%. The gamma dose rate at selected locations inside the dry cell was measured using radiochromic films and the results indicate slightly higher dose rates than predicted from the model. This is because the model calculated only prompt gamma dose rates during reactor operation while the radiochromic films measured gammas from activation products and fission product decayed gammas. The model was also used to calculate the neutron energy spectra for the energy range from 0.001 eV- 20 MeV. (authors)

  1. Cross Sections Calculations of ( d, t) Nuclear Reactions up to 50 MeV

    NASA Astrophysics Data System (ADS)

    Tel, E.; Yiğit, M.; Tanır, G.

    2013-04-01

    In nuclear fusion reactions two light atomic nuclei fuse together to form a heavier nucleus. Fusion power is the power generated by nuclear fusion processes. In contrast with fission power, the fusion reaction processes does not produce radioactive nuclides. The fusion will not produce CO2 or SO2. So the fusion energy will not contribute to environmental problems such as particulate pollution and excessive CO2 in the atmosphere. Fusion powered electricity generation was initially believed to be readily achievable, as fission power had been. However, the extreme requirements for continuous reactions and plasma containment led to projections being extended by several decades. In 2010, more than 60 years after the first attempts, commercial power production is still believed to be unlikely before 2050. Although there have been significant research and development studies on the inertial and magnetic fusion reactor technology, there is still a long way to go to penetrate commercial fusion reactors to the energy market. In the fusion reactor, tritium self-sufficiency must be maintained for a commercial power plant. Therefore, for self-sustaining (D-T) fusion driver tritium breeding ratio should be greater than 1.05. Working out the systematics of ( d, t) nuclear reaction cross sections is of great importance for the definition of the excitation function character for the given reaction taking place on various nuclei at different energies. Since the experimental data of charged particle induced reactions are scarce, self-consistent calculation and analyses using nuclear theoretical models are very important. In this study, ( d, t) cross sections for target nuclei 19F, 50Cr, 54Fe, 58Ni, 75As, 89Y, 90Zr, 107Ag, 127I, 197Au and 238U have been investigated up to 50 MeV deuteron energy. The excitation functions for ( d, t) reactions have been calculated by pre-equilibrium reaction mechanism. Calculation results have been also compared with the available measurements in

  2. New approach to analyzing and evaluating cross sections for partial photoneutron reactions

    SciTech Connect

    Varlamov, V. V. Ishkhanov, B. S.; Orlin, V. N.

    2012-11-15

    The presence of substantial systematic discrepancies between the results of different experiments devoted to determining cross sections for partial photoneutron reactions-first of all, ({gamma}, n), ({gamma}, 2n), and ({gamma}, 3n) reactions-is a strong motivation for studying the reliability and authenticity of these data and for developing methods for taking into account and removing the discrepancies in question. In order to solve the first problem, we introduce objective absolute criteria involving transitional photoneutron-multiplicity functions F{sub 1}, F{sub 2}, F{sub 3}, Horizontal-Ellipsis ; by definition, their values cannot exceed 1.0, 0.5, 0.33, Horizontal-Ellipsis , respectively. With the aim of solving the second problem, we propose a new experimental-theoretical approach. In this approach, reaction cross sections are evaluated by simultaneously employing experimental data on the cross section for the total photoneutron yield, {sigma}{sup expt}({gamma}, xn) = {sigma}{sup expt}({gamma}, n) + 2{sigma}{sup expt}({gamma}, 2n) + 3{sigma}{sup expt}({gamma}, 3n) + Horizontal-Ellipsis , which are free from drawbacks plaguing experimental methods for sorting neutrons in multiplicity, and the results obtained by calculating the functions F{sub theor}{sup 1}, F{sub theor}{sup 2}, F{sub theor}{sup 3}, Horizontal-Ellipsis on the basis of the modern model of photonuclear reactions. The reliability and authenticity of data on the cross sections for ({gamma}, n), ({gamma}, 2n), and ({gamma}, 3n) partial reactions-{sigma}{sup eval}({gamma}, in) = F{sub i}{sup theor}{sigma}{sup expt}({gamma}, xn)-were evaluated for the {sup 90}Zr, {sup 115}In, {sup 112,114,116,117,118,119,120,122,124}Sn, {sup 159}Tb, and {sup 197}Au nuclei.

  3. A Re-Analysis of Historical Los Alamos Critical Assembly Reaction Rate Measurements

    NASA Astrophysics Data System (ADS)

    Kahler, A. C.; MacInnes, M.; Chadwick, M. B.

    2016-02-01

    Starting in the 1950s and continuing into the early 1970s, a number of foil irradiations and fission chamber measurements were made in a variety of Fast critical assemblies at Los Alamos National Laboratory. These include (i) Godiva, a bare HEU spherical assembly; (ii) Flattop-25, a spherical assembly consisting of an HEU core and a natural uranium reflector; (iii) Jezebel, a bare 239Pu assembly; and (iv) Flattop-Pu, a spherical assembly consisting of a 239Pu core and a natural uranium reflector. In most instances the irradiations occur at or near the center of the assembly, but in selected instances data were obtained for a radial traverse extending into the Flattop reflector region. Measurements were made for a number of threshold reactions, including 45Sc(n,2n)44mSc, 51V(n,α)48Sc, 75As(n,2n)74As, 89Y(n,2n)88Y, 90Zr(n,2n)89Zr, 103Rh(n,2n)102gRh, 107Ag(n,2n)106mAg, 169Tm(n,2n)168Tm, 175Lu(n,2n)174Lu, 191Ir(n,2n)190Ir, 197Au(n,2n)196Au, 203Tl(n,2n)202Tl, 204Pb(n,2n)203Pb and 238U(n,2n)237U. Fission ratio data for 238U(n,f)/235U(n,f) and 239Pu(n,f)/235U(n,f) were also obtained. We report C/E values from MCNP6 calculations using ENDF/B-VII.1 and IRDFF-v1.03 cross section data.

  4. Application of the new MultiTrans SP3 radiation transport code in BNCT dose planning.

    PubMed

    Kotiluoto, P; Hiisamäki, P; Savolainen, S

    2001-09-01

    Dose planning in boron neutron capture therapy (BNCT) is a complex problem and requires sophisticated numerical methods. In the framework of the Finnish BNCT project, new deterministic three-dimensional radiation transport code MultiTrans SP3 has been developed at VTT Chemical Technology, based on a novel application of the tree multigrid technique. To test the applicability of this new code in a realistic BNCT dose planning problem, cylindrical PMMA (polymethyl-methacrylate) phantom was chosen as a benchmark case. It is a convenient benchmark, as it has been modeled by several different codes, including well-known DORT and MCNP. Extensive measured data also exist. In this paper, a comparison of the new MultiTrans SP3 code with other methods is presented for the PMMA phantom case. Results show that the total neutron dose rate to ICRU adult brain calculated by the MultiTrans SP3 code differs less than 4% in 2 cm depth in phantom (in thermal maximum) from the DORT calculation. Results also show that the calculated 197Au(n,gamma) and 55Mn(n,gamma) reaction rates in 2 cm depth in phantom differ less than 4% and 1% from the measured values, respectively. However, the photon dose calculated by the MultiTrans SP3 code seems to be incorrect in this PMMA phantom case, which requires further studying. As expected, the deterministic MultiTrans SP3 code is over an order of magnitude faster than stochastic Monte Carlo codes (with similar resolution), thus providing a very efficient tool for BNCT dose planning. PMID:11585221

  5. Comparative study of metal and non-metal ion implantation in polymers: Optical and electrical properties

    NASA Astrophysics Data System (ADS)

    Resta, V.; Quarta, G.; Farella, I.; Maruccio, L.; Cola, A.; Calcagnile, L.

    2014-07-01

    The implantation of 1 MeV metal (63Cu+, 107Ag+, 197Au+) and non-metal (4He+, 12C+) ions in a polycarbonate (PC) matrix has been studied in order to evaluate the role of ion species in the modification of optical and electrical properties of the polymer. When the ion fluence is above ∼1 × 1013 ions cm-2, the threshold for latent tracks overlapping is overcome and π-bonded carbon clusters grow and aggregate forming a network of conjugated Cdbnd C bonds. For fluences around 1 × 1017 ions cm-2, the aggregation phenomena induce the formation of amorphous carbon and/or graphite like structures. At the same time, nucleation of metal nanoparticles (NPs) from implanted species can take place when the supersaturation threshold is overcome. The optical absorption of the samples increases in the visible range and the optical band gap redshifts from 3.40 eV up to 0.70 eV mostly due to the carbonization process and the formation of C0x clusters and cluster aggregates. Specific structures in the extinction spectra are observed when metal ions are selected in contrast to the non-metal ion implanted PC, thus revealing the possible presence of noble metal based NPs interstitial to the C0x cluster network. The corresponding electrical resistance decreases much more when metal ions are implanted with at least a factor of 2 orders of magnitude difference than the non-metal ions based samples. An absolute value of ∼107 Ω/sq has been measured for implantation with metals at doses higher than 5 × 1016 ions cm-2, being 1017 Ω/sq the corresponding sheet resistance for pristine PC.

  6. Violent collisions and multifragment final states in the [sup 40]Ca+[sup 40]Ca reaction at 35 MeV/nucleon

    SciTech Connect

    Hagel, K.; Gonin, M.; Wada, R.; Natowitz, J.B.; Haddad, F.; Lou, Y.; Gui, M.; Utley, D.; Xiao, B.; Li, J. ); Nebbia, G.; Fabris, D.; Prete, G.; Ruiz, J. ); Drain, D.; Chambon, B.; Cheynis, B.; Guinet, D.; Hu, X.C.; Demeyer, A.; Pastor, C. ); Giorni, A.; Lleres, A.; Stassi, P.; Viano, J.B. ); Gonthier, P. )

    1994-10-01

    The 4[pi] multidetector AMPHORA has been used to measure yield distributions and energy spectra for products of the collisions in the reactions of [sup 40]Ca with [sup 40]Ca at 35 MeV/nucleon. Events of high multiplicity ([ge]10) for which [ge]85% of the total entrance channel atomic number is detected have been isolated and found to result from the most violent collisions which lead to excitation energies near 6 MeV/nucleon. A large fraction of these collisions lead to multifragment final states. A detailed comparison of the experimental data with results of various models indicates that statistical models which allow for expansion of the system or treat the multifragmentation process as a simultaneous disassembly are more successful than normal sequential binary models at reproducing the yield data and the event complexity inherent in the multifragment events. Quantum molecular dynamic (QMD) calculations are found to provide generally good agreement with the data but overestimate the proton and neutron emission. The agreement is significantly improved if an appropriate afterburner is used to deexcite the separated primary QMD fragments. The sensitivity of such hybrid calculations to the assumed matching time between the dynamical calculation and the afterburner has been explored. The experimentally filtered QMD calculations which provide good agreement with the experimental observables suggest that the most complex events observed in this work come not from the most central collisions, which decay more by light particle emission, but from a region of impact parameter [ital b]/[ital b][sub max]=0.5. This suggests that angular momentum effects play an important role in the multifragment decay modes. A comparison of the present results with those for projectile fragmentation in intermediate impact parameter collisions of 600 MeV/nucleon [sup 197]Au with Cu indicates that a similar multifragmenting system is produced in the two very different reaction systems.

  7. Recent results in relativistic heavy ion collisions: from 'a new state of matter' to 'the perfect fluid'

    NASA Astrophysics Data System (ADS)

    Tannenbaum, M. J.

    2006-07-01

    Experimental physics with relativistic heavy ions dates from 1992 when a beam of 197Au of energy greater than 10 A GeV/c first became available at the Alternating Gradient Synchrotron at Brookhaven National Laboratory (BNL) soon followed in 1994 by a 208Pb beam of 158A GeV/c at the Super Proton Synchrotron at CERN (European Center for Nuclear Research). Previous pioneering measurements at the Berkeley Bevalac (Gutbrod et al 1989 Rep. Prog. Phys. 52 1267-132) in the late 1970s and early 1980s were at much lower bombarding energies (<~1A GeV/c) where nuclear breakup rather than particle production is the dominant inelastic process in A+A collisions. More recently, starting in 2000, the relativistic heavy ion collider at BNL has produced head-on collisions of two 100 A GeV beams of fully stripped Au ions, corresponding to nucleon-nucleon centre-of-mass (cm) energy, \\sqrt{s_NN}=200\\,GeV , total cm energy 200 A GeV. The objective of this research program is to produce nuclear matter with extreme density and temperature, possibly resulting in a state of matter where the quarks and gluons normally confined inside individual nucleons (r < 1 fm) are free to act over distances an order of magnitude larger. Progress from the period 1992 to the present will be reviewed, with reference to previous results from light ion and proton-proton collisions where appropriate. Emphasis will be placed on the measurements which formed the basis for the announcements by the two major laboratories: 'A new state of matter', by CERN on Febraury 10 2000 and 'The perfect fluid' by BNL on April 19 2005.

  8. The 2014 ALMA Long Baseline Campaign: Observations of Asteroid 3 Juno at 60 Kilometer Resolution

    NASA Astrophysics Data System (ADS)

    ALMA Partnership; Hunter, T. R.; Kneissl, R.; Moullet, A.; Brogan, C. L.; Fomalont, E. B.; Vlahakis, C.; Asaki, Y.; Barkats, D.; Dent, W. R. F.; Hills, R. E.; Hirota, A.; Hodge, J. A.; Impellizzeri, C. M. V.; Liuzzo, E.; Lucas, R.; Marcelino, N.; Matsushita, S.; Nakanishi, K.; Pérez, L. M.; Phillips, N.; Richards, A. M. S.; Toledo, I.; Aladro, R.; Broguiere, D.; Cortes, J. R.; Cortes, P. C.; Espada, D.; Galarza, F.; Garcia-Appadoo, D.; Guzman-Ramirez, L.; Hales, A. S.; Humphreys, E. M.; Jung, T.; Kameno, S.; Laing, R. A.; Leon, S.; Marconi, G.; Mignano, A.; Nikolic, B.; Nyman, L.-A.; Radiszcz, M.; Remijan, A.; Rodón, J. A.; Sawada, T.; Takahashi, S.; Tilanus, R. P. J.; Vila Vilaro, B.; Watson, L. C.; Wiklind, T.; De Gregorio-Monsalvo, I.; Di Francesco, J.; Mangum, J.; Francke, H.; Gallardo, J.; Garcia, J.; Gonzalez, S.; Hill, T.; Kaminski, T.; Kurono, Y.; Lopez, C.; Morales, F.; Plarre, K.; Randall, S.; van kempen, T.; Videla, L.; Villard, E.; Andreani, P.; Hibbard, J. E.; Tatematsu, K.

    2015-07-01

    We present Atacama Large Millimeter/submillimeter Array (ALMA) 1.3 mm continuum images of the asteroid 3 Juno obtained with an angular resolution of 0\\buildrel{\\prime\\prime}\\over{.} 042 (60 km at 1.97 AU). The data were obtained over a single 4.4 hr interval, which covers 60% of the 7.2 hr rotation period, approximately centered on local transit. A sequence of 10 consecutive images reveals continuous changes in the asteroid's profile and apparent shape, in good agreement with the sky projection of the three-dimensional model of the Database of Asteroid Models from Inversion Techniques. We measure a geometric mean diameter of 259 ± 4 km, in good agreement with past estimates from a variety of techniques and wavelengths. Due to the viewing angle and inclination of the rotational pole, the southern hemisphere dominates all of the images. The median peak brightness temperature is 215 ± 13 K, while the median over the whole surface is 197 ± 15 K. With the unprecedented resolution of ALMA, we find that the brightness temperature varies across the surface with higher values correlated to the subsolar point and afternoon areas and lower values beyond the evening terminator. The dominance of the subsolar point is accentuated in the final four images, suggesting a reduction in the thermal inertia of the regolith at the corresponding longitudes, which are possibly correlated to the location of the putative large impact crater. These results demonstrate ALMA's potential to resolve thermal emission from the surface of main belt asteroids and to measure accurately their position, geometric shape, rotational period, and soil characteristics. .

  9. Multifragmentation in intermediate energy {sup 129}Xe-induced heavy-ion reactions

    SciTech Connect

    Tso, Kin

    1996-05-01

    The {sup 129}Xe-induced reactions on {sup nat}Cu, {sup 89}Y, {sup 165}Ho, and {sup 197}Au at bombarding energies of E/A = 40 & 60 MeV have been studied theoretically and experimentally in order to establish the underlying mechanism of multifragmentation at intermediate energy heavy-Ion collisions. Nuclear disks formed in central heavy-ion collisions, as simulated by means of Boltzmann-like kinetic equations, break up into several fragments due to a new kind of Rayleigh-like surface instability. A sheet of liquid, stable in the limit of non-interacting surfaces, is shown to become unstable due to surface-surface interactions. The onset of this instability is determined analytically. A thin bubble behaves like a sheet and is susceptible to the surface instability through the crispation mode. The Coulomb effects associated with the depletion of charges in the central cavity of nuclear bubbles are investigated. The onset of Coulomb instability is demonstrated for perturbations of the radial mode. Experimental intermediate-mass-fragment multiplicity distributions for the {sup 129}Xe-induced reactions are shown to be binomial at each transverse energy. From these distributions, independent of the specific target, an elementary binary decay probability p can be extracted that has a thermal dependence. Thus it is inferred that multifragmentation is reducible to a combination of nearly independent emission processes. If sequential decay is assumed, the increase of p with transverse energy implies a contraction of the emission time scale. The sensitivity of p to the lower Z threshold in the definition of intermediate-mass-fragments points to a physical Poisson simulations of the particle multiplicities show that the weak auto-correlation between the fragment multiplicity and the transverse energy does not distort a Poisson distribution into a binomial distribution. The effect of device efficiency on the experimental results has also been studied.

  10. Quantitative analysis of nuclear K-x-ray satellites for Z=50--83

    SciTech Connect

    Smolorz, J.; Hoppenau, S.; Roehl, S.; Schoenfeldt, W.A.; Dost, M.

    1980-01-01

    K-x-ray nuclear-satellite cross sections are reported for /sup 120/Sn, /sup 165/Ho, /sup 169/Tm, /sup 181/Ta, /sup 197/Au, /sup 208/Pb, and /sup 209//sub 83/Bi bombarded with 17.5--22.5-MeV ..cap alpha.. particles. Depending on target and energy, between 19 and 92% of these cross sections or those of /sup 206//sub 82/Pb and /sup 207//sub 82/Pb can be related to known nuclear decays in the recoils. Also deduced was the number of K-shell vacancies per reaction as a function of atomic number, which varies from 0.1 to 1.7, with pronounced minima at the shell closures Z=50 and 82. The system /sup 181//sub 73/Ta+..cap alpha.. at 18.5- and 20.5-MeV bombarding energy is studied in an x-ray-..gamma.. coincidence experiment selecting the (..cap alpha..,2n) reaction channel. A general procedure for complete cascade analysis is formulated. It emerges that (101 +- 13) % and (105 +- 8) % of the satellite intensity at 18.5 and 20.5 MeV, respectively, originate in converted transitions in the excited recoil. This accuracy shows that the study of converted continuum transitions by nuclear x-ray satellites is made possible by use of the algorithm for cascade analysis developed here. Also given are a decay scheme of /sup 184//sub 75/Re, hitherto unknown, and a number of new transitions completing the decay scheme of /sup 183//sub 75/Re.

  11. Electronic stopping power for heavy ions in SiC and SiO2

    SciTech Connect

    Jin, Ke; Zhang, Yanwen; Zhu, Zihua; Grove, David A.; Xue, Haizhou; Xue, Jianming; Weber, William J

    2014-01-01

    Accurate information of electronic stopping power is fundamental for broad advances in electronic industry, space exploration, national security, and sustainable energy technologies. The Stopping and Range of Ions in Matter (SRIM) code has been widely applied to predict stopping powers and ion distributions for decades. Recent experimental results have, however, shown considerable errors in the SRIM predictions for stopping of heavy ions in compounds containing light elements, indicating an urgent need to improve current stopping power models. The electronic stopping powers of 35Cl, 80Br, 127I, and 197Au ions are experimentally determined in two important functional materials, SiC and SiO2, from tens to hundreds keV/u based on a single ion technique. By combining with the reciprocity theory, new electronic stopping powers are suggested in a region from 0 to 15 MeV, where large deviations from SRIM predictions are observed. For independent experimental validation of the electronic stopping powers we determined, Rutherford backscattering spectrometry (RBS) and secondary ion mass spectrometry (SIMS) are utilized to measure the depth profiles of implanted Au ions in SiC with energies from 700 keV to 15 MeV. The measured ion distributions from both RBS and SIMS are considerably deeper (up to ~30%) than the predictions from the commercial SRIM code. In comparison, the new electronic stopping power values are utilized in a modified TRIM-85 (the original version of the SRIM) code, M-TRIM, to predict ion distributions, and the results are in good agreement with the experimentally measured ion distributions.

  12. Validation of dose planning calculations for boron neutron capture therapy using cylindrical and anthropomorphic phantoms

    NASA Astrophysics Data System (ADS)

    Koivunoro, Hanna; Seppälä, Tiina; Uusi-Simola, Jouni; Merimaa, Katja; Kotiluoto, Petri; Serén, Tom; Kortesniemi, Mika; Auterinen, Iiro; Savolainen, Sauli

    2010-06-01

    In this paper, the accuracy of dose planning calculations for boron neutron capture therapy (BNCT) of brain and head and neck cancer was studied at the FiR 1 epithermal neutron beam. A cylindrical water phantom and an anthropomorphic head phantom were applied with two beam aperture-to-surface distances (ASD). The calculations using the simulation environment for radiation application (SERA) treatment planning system were compared to neutron activation measurements with Au and Mn foils, photon dose measurements with an ionization chamber and the reference simulations with the MCNP5 code. Photon dose calculations using SERA differ from the ionization chamber measurements by 2-13% (disagreement increased along the depth in the phantom), but are in agreement with the MCNP5 calculations within 2%. The 55Mn(n,γ) and 197Au(n,γ) reaction rates calculated using SERA agree within 10% and 8%, respectively, with the measurements and within 5% with the MCNP5 calculations at depths >0.5 cm from the phantom surface. The 55Mn(n,γ) reaction rate represents the nitrogen and boron depth dose within 1%. Discrepancy in the SERA fast neutron dose calculation (of up to 37%) is corrected if the biased fast neutron dose calculation option is not applied. Reduced voxel cell size (<=0.5 cm) improves the SERA calculation accuracy on the phantom surface. Despite the slight overestimation of the epithermal neutrons and underestimation of the thermal neutrons in the beam model, neutron calculation accuracy with the SERA system is sufficient for reliable BNCT treatment planning with the two studied treatment distances. The discrepancy between measured and calculated photon dose remains unsatisfactorily high for depths >6 cm from the phantom surface. Increasing discrepancy along the phantom depth is expected to be caused by the inaccurately determined effective point of the ionization chamber.

  13. Establishment of a trimodality analytical platform for tracing, imaging and quantification of gold nanoparticles in animals by radiotracer techniques.

    PubMed

    Chen, Chien-Hung; Lin, Fong-Sian; Liao, Wei-Neng; Liang, Sanching L; Chen, Min-Hua; Chen, Yo-Wen; Lin, Wan-Yu; Hsu, Ming-Hua; Wang, Mei-Ya; Peir, Jinn-Jer; Chou, Fong-In; Chen, Ching-Ya; Chen, Sih-Yu; Huang, Su-Chin; Yang, Mo-Hsiung; Hueng, Dueng-Yuan; Hwu, Yeukuang; Yang, Chung-Shi; Chen, Jen-Kun

    2015-01-01

    This study aims to establish a (198)Au-radiotracer technique for in vivo tracing, rapid quantification, and ex vivo visualization of PEGylated gold nanoparticles (GNPs) in animals, organs and tissue dissections. The advantages of GNPs lie in its superior optical property, biocompatibility and versatile conjugation chemistry, which are promising to develop diagnostic probes and drug delivery systems. (198)Au is used as a radiotracer because it simultaneously emits beta and gamma radiations with proper energy and half-life; therefore, (198)Au can be used for bioanalytical purposes. The (198)Au-tagged radioactive gold nanoparticles ((198)Au-GNPs) were prepared simply by irradiating the GNPs in a nuclear reactor through the (197)Au(n,γ)(198)Au reaction and subsequently the (198)Au-GNPs were subjected to surface modification with polyethylene glycol to form PEGylated (198)Au-GNPs. The (198)Au-GNPs retained physicochemical properties that were the same as those of GNP before neutron irradiation. Pharmacokinetic and biodisposition studies were performed by intravenously injecting three types of (198)Au-GNPs with or without PEGylation into mice; the γ radiation in blood specimens and dissected organs was then measured. The (198)Au-radiotracer technique enables rapid quantification freed from tedious sample preparation and shows more than 95% recovery of injected GNPs. Clinical gamma scintigraphy was proved feasible to explore spatial- and temporal-resolved biodisposition of (198)Au-GNPs in living animals. Moreover, autoradiography, which recorded beta particles from (198)Au, enabled visualizing the heterogeneous biodisposition of (198)Au-GNPs in different microenvironments and tissues. In this study, the (198)Au-radiotracer technique facilitated creating a trimodality analytical platform for tracing, quantifying and imaging GNPs in animals. PMID:25424326

  14. Beam-cooling methods in the NICA project

    NASA Astrophysics Data System (ADS)

    Kostromin, S. A.; Meshkov, I. N.; Sidorin, A. O.; Smirnov, A. V.; Trubnikov, G. V.; Shurkhno, N.

    2012-07-01

    The Nuclotron-based Ion Collider Facility (NICA) is a new accelerator complex under construction at the Joint Institute for Nuclear Research (JINR) for experiments with colliding beams of heavy ions up to gold at energies as high as 4.5 × 4.5 GeV/u aimed at studying hot and dense strongly interacting nuclear matter and searching for possible indications of the mixed phase state and critical points of phase transitions. This facility comprises an ion source of the electron-string type, a 3-MeV/u linear accelerator, a 600-MeV/u superconducting booster synchrotron (Booster), a Nuclotron (upgraded superconducting synchrotron with a maximum energy of 4.5 GeV/u for ions with the charge-to-mass ratio Z/ A = 1/3), and a collider consisting of two vertically separated superconducting rings with an average luminosity of 1027 cm-2 s-1 in an energy range over 3.0 GeV/u. Beam cooling is supposed to be used in two NICA elements, the Booster, and the collider rings. The Booster is intended for the storage of 197Au31+ ions to an intensity of about 4 × 109 particles; their acceleration to the energy 600 MeV/u, which is sufficient for the complete stripping of nuclei (an increase in the injection energy and the charge state of ions makes the requirements for vacuum conditions in the Nuclotron less stringent); and the formation of the necessary beam emittance using the electron cooling system. Two independent beam-cooling systems, a stochastic one and an electron one, are supposed to be used in the collider. The parameters of the cooling systems, the optimum mode of operation for the collider, and the arrangement and design of the elements of the systems are discussed.

  15. Determination of effective resonance energy for the 193Ir(n,γ)194Ir reaction by the cadmium ratio method

    NASA Astrophysics Data System (ADS)

    Budak, Mustafa Guray; Karadag, Mustafa; Yücel, Haluk

    2016-04-01

    In this work, the effective resonance energy, Ebarr -value for the 193Ir(n,γ)194Ir reaction was measured using cadmium ratio method. A dual monitor (197Au-98Mo), which has convenient resonance properties, was employed for characterization of the irradiation sites. Then analytical grade iridium oxide samples diluted with CaCO3 to lower neutron self-shielding effect stacked in small cylindrical Teflon boxes were irradiated once with a 1 mm thick Cd cylindrical box placed in a thermalized neutron field of an 241Am-Be neutron source then without it. The activities produced in samples during 193Ir(n,γ)194Ir reaction were measured using a p-type HPGe detector γ-ray spectrometer with a 44.8% relative efficiency. The correction factors for thermal, epithermal neutron self-shielding (Gth, Gepi), true coincidence summing (Fcoi) and gamma-ray self-absorption (Fs) effects were determined with appropriate approaches and programs. Thus, the experimental Ebarr -value was determined to be 2.65 ± 0.61 eV for 193Ir target nuclide. The recent data for Q0 and FCd values for Ebarr determination were based on k0-NAA online database. The present experimental Ebarr value was calculated and compared with more recent values for Q0 and FCd for 193Ir. Additionally, the Ebarr -values was theoretically calculated from the up-to-date resonance data obtained from ENDF/B VII library using two different approaches. Since there is no experimentally determined Ebarr -value for the 193Ir isotope, the results are compared with the calculated ones given in the literature.

  16. Nucleon-induced fission cross sections of heavy nuclei in the intermediate energy region

    NASA Astrophysics Data System (ADS)

    Prokofiev, Alexander V.

    Fission is the most important nuclear reaction for society at large today due to its use in energy production. However, this has raised the problem of how to treat the long-lived radioactive waste from nuclear reactors. A radical solution would be to change the composition of the waste into stable or short-lived nuclides, which could be done through nuclear transmutation. Such a concept requires accelerator-driven systems to be designed, where those for transmutation are reactor hybrids. This thesis is a contribution to the knowledge base for developing transmutation systems, specifically with respect to the computational modeling of the underlying nuclear reactions, induced by the incident and secondary particles. Intermediate energy fission cross sections are one important type of such data. Moreover, they are essential for understanding the fission process itself and related nuclear interactions. The experimental part of this work was performed at the neutron beam facility of The Svedberg Laboratory in Uppsala. Fission cross sections of 238U, 209Bi, natPb, 208Pb, 197Au, natW, and 181Ta were measured for neutrons in the range En = 30-160 MeV using thin-film breakdown counters for the fission fragment detection. A model was developed for the determination of the efficiency of such detectors. A compilation of existing data on proton-induced fission cross sections for nuclei from 165Ho to 239Pu was performed. The results, which constitute the main body of information in this field, were added to the worldwide EXFOR database. The dependences of the cross sections on incident energy and target nucleus were studied, which resulted in systematics that make it possible to give estimates for unmeasured nuclides. Nucleon-induced fission cross sections were calculated using an extended version of the cascade exciton model. A comparison with the systematics and the experimental data obtained in the present work revealed significant discrepancies. A modification of the model

  17. Influence of complex impurity centres on radiation damage in wide-gap metal oxides

    NASA Astrophysics Data System (ADS)

    Lushchik, A.; Lushchik, Ch.; Popov, A. I.; Schwartz, K.; Shablonin, E.; Vasil'chenko, E.

    2016-05-01

    Different mechanisms of radiation damage of wide-gap metal oxides as well as a dual influence of impurity ions on the efficiency of radiation damage have been considered on the example of binary ionic MgO and complex ionic-covalent Lu3Al5O12 single crystals. Particular emphasis has been placed on irradiation with ∼2 GeV heavy ions (197Au, 209Bi, 238U, fluence of 1012 ions/cm2) providing extremely high density of electronic excitations within ion tracks. Besides knock-out mechanism for Frenkel pair formation, the additional mechanism through the collapse of mobile discrete breathers at certain lattice places (e.g., complex impurity centres) leads to the creation of complex defects that involve a large number of host atoms. The experimental manifestations of the radiation creation of intrinsic and impurity antisite defects (Lu|Al or Ce|Al - a heavy ion in a wrong cation site) have been detected in LuAG and LuAG:Ce3+ single crystals. Light doping of LuAG causes a small enhancement of radiation resistance, while pair impurity centres (for instance, Ce|Lu-Ce|Al or Cr3+-Cr3+ in MgO) are formed with a rise of impurity concentration. These complex impurity centres as well as radiation-induced intrinsic antisite defects (Lu|Al strongly interacting with Lu in a regular site) tentatively serve as the places for breathers collapse, thus decreasing the material resistance against dense irradiation.

  18. NEUTRON CROSS SECTION EVALUATIONS OF FISSION PRODUCTS BELOW THE FAST ENERGY REGION

    SciTech Connect

    OH,S.Y.; CHANG,J.; MUGHABGHAB,S.

    2000-05-11

    Neutron cross section evaluations of the fission-product isotopes, {sup 95}Mo, {sup 99}Tc, {sup 101}Ru, {sup 103}Rh, {sup 105}Pd, {sup 109}Ag, {sup 131}Xe, {sup 133}Cs, {sup 141}Pr, {sup 141}Nd, {sup 147}Sm, {sup 149}Sm, {sup 150}Sm, {sup 151}Sm, {sup 152}Sm, {sup 153}Eu, {sup 155}Gd, and {sup 157}Gd were carried out below the fast neutron energy region within the framework of the BNL-KAERI international collaboration. In the thermal energy region, the energy dependence of the various cross-sections was calculated by applying the multi-level Breit-Wigner formalism. In particular, the strong energy dependence of the coherent scattering lengths of {sup 155}Gd and {sup 157}Gd were determined and were compared with recent calculations of Lynn and Seeger. In the resonance region, the recommended resonance parameters, reported in the BNL compilation, were updated by considering resonance parameter information published in the literature since 1981. The s-wave and, if available, p-wave reduced neutron widths were analyzed in terms of the Porter-Thomas distribution to determine the average level spacings and the neutron strength functions. Average radiative widths were also calculated from measured values of resolved energy resonances. The average resonance parameters determined in this study were compared with those in the BNL and other compilations, as well as the ENDF/B-VI, JEF-2.2, and JENDL-3.2 data libraries. The unresolved capture cross sections of these isotopes, computed with the determined average resonance parameters, were compared with measurements, as well as the ENDF/B-VI evaluations. To achieve agreement with the measurements, in a few cases minor adjustments in the average resonance parameters were made. Because of astrophysical interest, the Maxwellian capture cross sections of these nuclides at a neutron temperature of 30 keV were computed and were compared with other compilations and evaluations.

  19. Structural changes and superconducting properties of Gd1-2xPrxCaxBa2Cu3O7-δ HTSCs

    NASA Astrophysics Data System (ADS)

    Udomkan, N.; Winotai, P.; Suryanarayanan, R.; Charoenthai, N.

    2005-10-01

    We report on structural changes and the properties of Gd1-2xPrxCaxBa2Cu3O7-δ (0<=x<=0.3) high temperature superconductors which were prepared and characterized. The transition temperature (Tc) was found to decrease roughly linearly with respect to the Pr and Ca concentration x. 65Cu2+(3d9) and 63Cu2+(3d9) ions from impurity phase BaCuO2 give rise to X-band electron spin resonant (ESR) two-quartet absorption peaks centred at ~310 mT (g~2.020) which are superposed by the broad ESR peak of Gd3+(4f7) at g~2.000 in the undoped Gd123. Both sets of ESR peaks shift towards low fields as the temperature is lowered, which is due to the change in crystal field experienced by the ions. It should be noted here that even at 77 K there still is no magnetic ordering from Gd3+ ions. However, at x = 0.025 doping, a new six-peak hyperfine multiplet ESR signal arising from 141Pr4+ (4f1,S = 1/2,I = 5/2) appears at ~323 mT (g~2.029). Typical simulated ESR parameters of Gd3+ in Gd1-2xPrxCaxBa2Cu3O7-δ at x = 0.025, are gx = 2.4879, gy = 2.3921 and gz = 2.2590, Axx = 12.50, Ayy = 23.50, Azz = 32.00 G and the zero-field splitting parameter (D) of 66.0 G, respectively. This signal arises from some Pr ions entering the Gd site with a valence of four, thus lending support to the hole-filling and pair-breaking models.

  20. Cross sections for the formation of {sup 195}Hg{sup m,g}, {sup 197}Hg{sup m,g}, and {sup 196}Au{sup m,g} in {alpha} and {sup 3}He-particle induced reactions on Pt: Effect of level density parameters on the calculated isomeric cross-section ratio

    SciTech Connect

    Sudar, S.; Qaim, S.M.

    2006-03-15

    Excitation functions were measured for the reactions {sup nat}Pt({sup 3}He,xn){sup 195}Hg{sup m,g},{sup nat}Pt({sup 3}He,xn){sup 197}Hg{sup m,g},{sup nat}Pt({sup 3}He,= x){sup 196}Au{sup m,g}, and {sup nat}Pt({alpha},xn){sup 197}Hg{sup m,g} over the energy range of 18-35 MeV for {sup 3}He particles and 17-26 MeV for {alpha} particles. The reactions {sup 197}Au(p,n){sup 197}Hg{sup m,g} were also investigated over the proton energy range of 6-20 MeV. The three projectiles were produced at the Juelich variable-energy compact cyclotron (CV 28). Use was made of the activation technique in combination with conventional high-resolution as well as low-energy HPGe-detector {gamma}-ray spectroscopy. For most of the reactions, the present measurements provide the first consistent sets of data. From the available experimental data, isomeric cross-section ratios were determined for the above-mentioned reactions. Nuclear model calculations using the code STAPRE, which employs the Hauser-Feshbach (statistical model) and exciton model (precompound effects) formalisms, were undertaken to describe the formation of both the isomeric and the ground states of the products. The calculations were compared with the results of the EMPIRE-II code. The excitation functions of the ({sup 3}He,xn) and ({alpha},xn) processes are described well by the theory. In the case of ({sup 3}He,pxn) reactions, however, considerable deviations were observed between the experiment and the theory, presumably due to strong contributions from direct interactions. A description of the isomeric cross-section ratio by the model was possible only with a very low value of {eta}, i.e., the {theta}{sub eff}/{theta}{sub rig} ratio. A mass dependence of {eta} is proposed.

  1. Nuclear reactions with 11C and 14O radioactive ion beams

    SciTech Connect

    Guo, Fanqing

    2004-12-09

    Radioactive ion beams (RIBs) have been shown to be a useful tool for studying proton-rich nuclides near and beyond the proton dripline and for evaluating nuclear models. To take full advantage of RIBs, Elastic Resonance Scattering in Inverse Kinematics with Thick Targets (ERSIKTT), has proven to be a reliable experimental tool for investigations of proton unbound nuclei. Following several years of effort, Berkeley Experiments with Accelerated Radioactive Species (BEARS), a RIBs capability, has been developed at the Lawrence Berkeley National Laboratory's 88-Inch Cyclotron. The current BEARS provides two RIBs: a 11C beam of up to 2x108 pps intensity on target and an 14O beam of up to 3x104 pps intensity. While the development of the 11C beam has been relatively easy, a number of challenges had to be overcome to obtain the 14O beam. The excellent 11C beam has been used to investigate several reactions. The first was the 197Au(11C,xn)208-xnAt reaction, which was used to measure excitation functions for the 4n to 8n exit channels. The measured cross sections were generally predicted quite well using the fusion-evaporation code HIVAP. Possible errors in the branching ratios of ?? decays from At isotopes as well as the presence of incomplete fusion reactions probably contribute to specific overpredictions. 15F has been investigated by the p(14O,p)14O reaction with the ERSIKTT technology. Several 14O+p runs have been performed. Excellent energy calibration was obtained using resonances from the p(14N,p)14N reaction in inverse kinematics, and comparing the results to those obtained earlier with normal kinematics. The differences between 14N+p and 14O+p in the stopping power function have been evaluated for better energy calibration. After careful calibration, the energy levels of 15F were fitted with an R-matrix calculation. Spins and parities were assigned to the two observed resonances. This new measurement of the 15F ground state supports the disappearance of the Z = 8

  2. Production of beams of neutron-rich nuclei between Ca and Ni using the ion-guide technique

    SciTech Connect

    Perajarvi, K.; Cerny, J.; Hager, U.; Hakala, J.; Huikari, J.; Jokinen, A.; Karvonen, P.; Kurpeta, J.; Lee, D.; Moore, I.; Penttila, H.; Popov, A.; Aysto, J.

    2004-09-28

    Since several elements between Z = 20-28 are refractory in their nature, their neutron-rich isotopes are rarely available as low energy Radioactive Ion Beams (RIB) in ordinary Isotope Separator On-Line facilities [1-4]. These low energy RIBs would be especially interesting to have available under conditions which allow high-resolution beta-decay spectroscopy, ion-trapping and laser-spectroscopy. As an example, availability of these beams would open a way for research which could produce interesting and important data on neutron-rich nuclei around the doubly magic {sup 78}Ni. One way to overcome the intrinsic difficulty of producing these beams is to rely on the chemically unselective Ion Guide Isotope Separator On-Line (IGISOL) technique [5]. Quasi- and deep-inelastic reactions, such as {sup 197}Au({sup 65}Cu,X)Y, could be used to produce these nuclei in existing IGISOL facilities, but before they can be successfully incorporated into the IGISOL concept their kinematics must be well understood. Therefore the reaction kinematics part of this study was first performed at the Lawrence Berkeley National Laboratory using its 88'' cyclotron and, based on those results, a specialized target chamber was built[6]. The target chamber shown in Fig. 1 was recently tested on-line at the Jyvaaskylaa IGISOL facility. Yields of mass-separated radioactive projectile-like species such as {sup 62,63}Co are about 0.8 ions/s/pnA, corresponding to about 0.06 % of the total IGISOL efficiency for the products that hit the Ni-degrader. (The current maximum 443 MeV {sup 65}Cu beam intensity at Jyvaaskylaa is about 20 pnA.) This total IGISOL efficiency is a product of two coupled loss factors, namely inadequate thermalization and the intrinsic IGISOL efficiency. In our now tested chamber, about 9 % of the Co recoils are thermalized in the owing He gas (p{sub He}=300 mbar) and about 0.7 % of them are converted into the mass-separated ion beams. In the future, both of these physical

  3. Non-spin-flip ( 3He, t) charge-exchange and isobaric analog states of actinide nuclei studied at θ = 0°, E( 3He) = 76 MeV and 200 MeV

    NASA Astrophysics Data System (ADS)

    Jänecke, J.; Becchetti, F. D.; van den Berg, A. M.; Berg, G. P. A.; Brouwer, G.; Greenfield, M. B.; Harakeh, M. N.; Hofstee, M. A.; Nadasen, A.; Roberts, D. A.; Sawafta, R.; Schippers, J. M.; Stephenson, E. J.; Stewart, D. P.; van der Werf, S. Y.

    1991-04-01

    The ( 3He, t) charge-exchange reaction has been studied at θ = 0° and bombarding energies of E( 3He) = 76.5 MeV and 200 MeV. Spectra were measured using magnetic analysis for target nuclei of 12, 13C, 16O, 19F, 28, 29, 30Si, 90Zr, 117, 120Sn, natTa, natW, 197Au, 208Pb, 230, 232Th, 234, 236, 238U and 244Pu. The measurements at 76.5 MeV concentrated on the isobaric analog states of several actinide nuclei, particularly on their widths and the branching ratios for proton decay. Cross sections, Q-values and total widths were determined for the transitions to the isobaric analog states. Coulomb displacement energies derived from the measured Q-values display the influence of deformed nuclear shapes. Escape widths Γ ↑ and spreading widths Γ ↓ of the isobaric analog states in five actinide nuclei were deduced from the measured proton-decay branching ratios. They were found to be in agreement with predictions which postulate isospin mixing via the Coulomb force with the ( T0-1)-component of the isovector giant monopole resonance. The measurements at 200 MeV were concerned with transitions to isobaric analog states in both light and heavy nuclei, including several actinide nuclei, but Gamow-Teller resonances and transitions to numerous other states were also observed. The measured cross sections for several transitions to isobaric analog states from 30Si to 208Pb were used to extract the effective interaction Vτ for non-spin-flip ( 3He, t) charge exchange at E( 3He) ≈ 200 MeV. The interaction strength Vτ decreases by a factor 0.6 when compared to previously measured values for the energy range E( 3He) = 65 to 90 MeV. An angular distribution from θτ = 0° to 16° for the transition to the isobaric analog state in 120Sb measured at E( 3He) = 200 MeV was found to be in very good agreement with microscopic calculations.

  4. Direct Quantification of Rare Earth Elements Concentrations in Urine of Workers Manufacturing Cerium, Lanthanum Oxide Ultrafine and Nanoparticles by a Developed and Validated ICP-MS

    PubMed Central

    Li, Yan; Yu, Hua; Zheng, Siqian; Miao, Yang; Yin, Shi; Li, Peng; Bian, Ying

    2016-01-01

    Rare earth elements (REEs) have undergone a steady spread in several industrial, agriculture and medical applications. With the aim of exploring a sensitive and reliable indicator of estimating exposure level to REEs, a simple, accurate and specific ICP-MS method for simultaneous direct quantification of 15 REEs (89Y, 139La, 140Ce, 141Pr, 146Nd, 147Sm, 153Eu, 157Gd, 159Tb, 163Dy, 165Ho, 166Er, 169Tm, 172Yb and 175Lu) in human urine has been developed and validated. The method showed good linearity for all REEs in human urine in the concentrations ranging from 0.001–1.000 μg∙L−1 with r2 > 0.997. The limits of detection and quantification for this method were in the range of 0.009–0.010 μg∙L−1 and 0.029–0.037 μg∙L−1, the recoveries on spiked samples of the 15 REEs ranged from 93.3% to 103.0% and the relative percentage differences were less than 6.2% in duplicate samples, and the intra- and inter-day variations of the analysis were less than 1.28% and less than 0.85% for all REEs, respectively. The developed method was successfully applied to the determination of 15 REEs in 31 urine samples obtained from the control subjects and the workers engaged in work with manufacturing of ultrafine and nanoparticles containing cerium and lanthanum oxide. The results suggested that only the urinary levels of La (1.234 ± 0.626 μg∙L−1), Ce (1.492 ± 0.995 μg∙L−1), Nd (0.014 ± 0.009 μg∙L−1) and Gd (0.023 ± 0.010 μg∙L−1) among the exposed workers were significantly higher (p < 0.05) than the levels measured in the control subjects. From these, La and Ce were the primary components, and accounted for 88% of the total REEs. Lanthanum comprised 27% of the total REEs while Ce made up the majority of REE content at 61%. The remaining elements only made up 1% each, with the exception of Dy which was not detected. Comparison with the previously published data, the levels of urinary La and Ce in workers and the control subjects show a higher trend

  5. Direct Quantification of Rare Earth Elements Concentrations in Urine of Workers Manufacturing Cerium, Lanthanum Oxide Ultrafine and Nanoparticles by a Developed and Validated ICP-MS.

    PubMed

    Li, Yan; Yu, Hua; Zheng, Siqian; Miao, Yang; Yin, Shi; Li, Peng; Bian, Ying

    2016-03-01

    Rare earth elements (REEs) have undergone a steady spread in several industrial, agriculture and medical applications. With the aim of exploring a sensitive and reliable indicator of estimating exposure level to REEs, a simple, accurate and specific ICP-MS method for simultaneous direct quantification of 15 REEs ((89)Y, (139)La, (140)Ce, (141)Pr, (146)Nd, (147)Sm, (153)Eu, (157)Gd, (159)Tb, (163)Dy, (165)Ho, (166)Er, (169)Tm, (172)Yb and (175)Lu) in human urine has been developed and validated. The method showed good linearity for all REEs in human urine in the concentrations ranging from 0.001-1.000 μg ∙ L(-1) with r² > 0.997. The limits of detection and quantification for this method were in the range of 0.009-0.010 μg ∙ L(-1) and 0.029-0.037 μg ∙ L(-1), the recoveries on spiked samples of the 15 REEs ranged from 93.3% to 103.0% and the relative percentage differences were less than 6.2% in duplicate samples, and the intra- and inter-day variations of the analysis were less than 1.28% and less than 0.85% for all REEs, respectively. The developed method was successfully applied to the determination of 15 REEs in 31 urine samples obtained from the control subjects and the workers engaged in work with manufacturing of ultrafine and nanoparticles containing cerium and lanthanum oxide. The results suggested that only the urinary levels of La (1.234 ± 0.626 μg ∙ L(-1)), Ce (1.492 ± 0.995 μg ∙ L(-1)), Nd (0.014 ± 0.009 μg ∙ L(-1)) and Gd (0.023 ± 0.010 μg ∙ L(-1)) among the exposed workers were significantly higher (p < 0.05) than the levels measured in the control subjects. From these, La and Ce were the primary components, and accounted for 88% of the total REEs. Lanthanum comprised 27% of the total REEs while Ce made up the majority of REE content at 61%. The remaining elements only made up 1% each, with the exception of Dy which was not detected. Comparison with the previously published data, the levels of urinary La and Ce in workers and

  6. Ion microprobe study of Au and Carlin-type trace metals in rhyolite melt inclusions from Eocene dikes and ash-flow tuff in northern Nevada

    NASA Astrophysics Data System (ADS)

    Watts, K. E.; Colgan, J. P.; John, D. A.; Henry, C.; Coble, M. A.; Hervig, R. L.

    2013-12-01

    Vigorous Eocene magmatism was coincident in space and time with the formation of large Carlin-type gold deposits in the Great Basin of the western U.S.A. However, it is not known if Eocene magmas were a potential source of metals for these economically valuable deposits. To investigate this possibility, we experimented with measurements of trace metals in quartz-hosted rhyolite melt inclusions from the 34 Ma Caetano caldera, source of the >1,100 km3 Caetano Tuff, and nearby 35.7 Ma rhyolite dikes temporally and spatially associated with the Cortez Hills Carlin-type gold deposit. We targeted a suite of trace elements (Au, Cu, Sb, Te, As) characteristic of Carlin-type gold deposits, using novel secondary-ion-mass-spectrometry (SIMS) techniques. Our experiments show that ppb levels of Au, and ppm to sub-ppm levels of Cu, Sb, Te and As, can be detected using a ~10 nA Cs+ primary beam focused to a ~30 μm spot size, calibrated with NIST-610-614 series glasses. Melt inclusion data obtained with a Cameca IMS 6f were compared with analyses of the same melt inclusions using a SHRIMP-RG to evaluate the reproducibility of the measurements, and the efficacy of high mass resolving power to remove isobaric interferences on the elements of interest. For Au, the higher mass resolving power of the SHRIMP-RG (~10,500 ΔM/M) was required to distinguish <10-20 ppb 'background' Au counts obtained with the 6f (~5,500 ΔM/M), possibly due to a 181Ta16O interference on 197Au from the Ta immersion lens. With the SHRIMP-RG, Au concentrations were reduced to zero in both the Caetano and Cortez melt inclusion datasets. However, we did detect numerous Cu-rich sulfide inclusions, including one with elevated Au counts in one of the Cortez melt inclusions. Given the rarity of this occurrence, it seems that Au was either very scarce in the host magma chambers, or lost to a vapor or sulfide phase prior to the time of melt inclusion entrapment. Concentrations of other Carlin-type elements (Cu, Sb

  7. The evolution of volatile production in C/2009 P1 (Garradd) during its 2011-2012 apparition

    NASA Astrophysics Data System (ADS)

    Gicquel, A.; Milam, S.; Cordiner, M.; Villanueva, G.; Charnley, S.; Coulson, I.; Remijan, A.; DiSanti, M.; Mumma, M.; Szutowicz, S.

    2014-07-01

    Comets are likely to be the most pristine objects in our Solar System. They provide a record of the physical and chemical conditions in the protosolar nebula between about 5 and 40 au during the epoch when the distinct cometary populations were being assembled (Festou et al. 2004; Jewitt 2004; Mumma & Charnley 2011). Cometary nuclei today reside in (at least) two distinct reservoirs, the Oort Cloud (OC) and the Kuiper Belt (KB). Past observations have shown that comets appear to contain a mixture of products from both interstellar and nebular chemistries and could also have been important for initiating prebiotic chemistry on the early Earth (Ehrenfreund & Charnley 2000). Although there are some differences, the volatile composition of cometary ices is generally similar to the inventory of molecules detected in the ices and gas of dense molecular clouds. Given the gradient in physical conditions expected across the proto-Solar nebula, chemical diversity in the comet population is to be expected. Here we report an analysis of long-term ground-based radio observations towards comet C/2009 P1 (Garradd). Comet C/2009 P1 Garradd is an OC comet that reached perihelion (at heliocentric distance R_h = 1.55 au) in late December 2011 and had its closest approach to the Earth on 5 March 2012. Like C/1995 O1 (Hale-Bopp) at 7.2 au, Garradd exhibited unusual activity at large R_h (8.68 au), displaying a 15'' diameter circular coma (IAUC 9062). It is well known that some comets exhibit volatile activity at large heliocentric distances, where water ice cannot sublime efficiently. Infrared (IRTF/CSHELL, Keck 2/NIRSPEC, and VLT/CRIRES) spectroscopy of Garradd showed clear CO (R1 & R2) emission near λ = 4.7 μ m (2150 cm^{-1}), as well as a suite of molecules (e.g., C_2H_6, CH_4, CH_3OH, H_2CO, HCN, C_2H_2, NH_3) that were also detected near or beyond R_h = 2 au (Villanueva et al. 2012; Paganini et al. 2012; DiSanti et al. 2014). We monitored the abundance of parent volatiles in Garradd at multiple epochs around the time of its closest approach to the Earth, using multiple facilities: the Arizona Radio Observatory's 12-m telescope, Kitt Peak, the SubMillimeter Telescope, the James Clerk Maxwell Telescope, and the Greenbank 100-m telescope (GBT), covering wavelengths of 20 cm, 3 cm, and 0.8-3 mm. Observations were taken between 28 December 2011 (R_h = 1.55 au, Δ = 1.97 au) and 28 November 2012 (R_h = 4.27 au, Δ = 4.26 au). GBT monitored OH as a proxy for H_2O activity, while the other facilities were used to study the primary volatiles (e.g., CH_3OH, H_2CO, HCN, HNC, CS, CO). The full analysis of these data, including the determination of the rotational temperatures, abundances, and the variation of given species with time, will be presented. Also, comparisons with other comets will be shown in order to constrain the chemical history on comets and add to the statistics for a taxonomic classification of these objects.

  8. Coast-to-interior gradients and recent trends in physical and chemical properties of near-surface snow and firn in northwest Greenland

    NASA Astrophysics Data System (ADS)

    Wong, G. J.; Osterberg, E. C.; Hawley, R. L.; Caughey, S. K.; Courville, Z.; Howley, J.; Lutz, E.; Overly, T. B.

    2013-12-01

    The Greenland Ice Sheet (GIS), which holds enough ice to raise global sea levels by approximately 7 m, is a major driver of Arctic and global climate. Observations over the past two decades have documented changes including notable increases in ice discharge, significant warming in coastal regions, and expanded areal extent of annual surface melt (e.g., Rignot and Thomas, 2002; Mote, 2007; Hanna and others, 2008). In contrast, observations document little change in temperature or accumulation in the central regions of the ice sheet (Hanna and others, 2008, 2011). The 1120 km-long Greenland Inland Traverse (GrIT), between Thule Air Base in northwest Greenland and Summit Station in central Greenland, is a logistics traverse that follows a nearly identical route taken by Carl Benson and the US Army Snow, Ice and Permafrost Research Establishment (SIPRE) between 1952 and 1955 (Benson, 1962). Observations from the SIPRE and GrIT traverses provide two snapshots of surface conditions across the northwest region of the GIS separated by 56 years. Hawley and others (in review) observe an increase in snow accumulation rates along the GrIT traverse route based on internal reflecting horizons in radar data dated with firn cores, with larger accumulation increases observed in the coastal region near Thule. Here we expand upon the analysis of Hawley and others (in review) by determining coast-to-interior gradients in snow accumulation, density, hardness (Rammsonde), and snow chemistry using samples from 18 snow pits and 3 firn cores collected during the 2010 and 2011 GrIT traverses. Snow pit and firn core samples were analyzed for trace element (23Na, 24Mg, 27Al, 32S, 39K, 44Ca, 47Ti, 51V, 52Cr, 55Mn, 56Fe, 59Co, 63Cu, 66Zn, 75As, 88Sr, 111Cd, 133Cs, 138Ba, 139La, 140Ce, 141Pr, 208Pb, 209Bi, 238U) concentrations and stable water isotope ratios (δD, δ18O), and were dated by seasonal oscillations in chemical concentrations and isotope ratios. We compare the GrIT data to those of

  9. Comparison of microconcentric and membrane-desolvation sample introduction systems for determination of low rare earth element concentrations in surface and subsurface waters using sector field inductively coupled plasma mass spectrometry

    NASA Astrophysics Data System (ADS)

    Chung, Chuan-Hsiung; Brenner, Isaac; You, Chen-Feng

    2009-09-01

    Analytical performances of a microconcentric nebulizer (MCN) and a membrane-desolvation sample introduction system (Aridus) were compared for determination of low concentrations of rare earth elements (REEs) in surface and subsurface waters using a double focusing sector field inductively coupled plasma mass spectrometer. Conventional figures of merit were employed, such as sensitivities, limits of detection (LOD), REE-O + formation, matrix induced interferences, long term signal variations, and recovery from spiked sea water samples and a pristine water CRM. Sensitivity as a function of mass for the MCN was quite flat with the exception of light REE (LREE +) which was dependent on REE-O + generation. Signal responses using the Aridus were enhanced by factors of 4-10. Large sensitivity enhancements were observed for 139La +, 140Ce + and 141Pr +, due to the attenuation of their REE-O + (where the Aridus 140Ce 16O +/ 140Ce + was three orders of magnitude lower than that determined using the MCN) as a result of water analysis reduction in the plasma. Despite higher sensitivities, Aridus LODs were not significantly different from those obtained using the MCN, and values varied from 0.05 to 0.2 ng L - 1 and 0.1 to 0.2 ng L - 1 for the MCN and Aridus systems, respectively. When using the MCN, LREE + signals were closely associated with REE-O bond strengths, implying that LREE-O + production and breakdown are related to the strength of REE-O bonds in REE-O + ions suggesting that medium REE (MREE)-O + and heavy REE (HREE)-O + if formed, were thermally unstable in the plasma. In the presence of conservative Na concentrations, MCN LREE + signal suppressions varied from about 15 to 25% and about 5 to 10% for MREE + and HREE +. In contrast, regular 15% signal suppressions for all REE + were observed for the Aridus. In the case of the MCN, more than one internal standard is required for compensation for these different effects, whereas a single internal standard ( 159Tb