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Sample records for 141pr 197au nattl

  1. Thermal-neutron cross sections and resonance integrals of 138Ba and 141Pr using Am-Be neutron source

    NASA Astrophysics Data System (ADS)

    Panikkath, Priyada; Mohanakrishnan, P.

    2016-09-01

    The thermal-neutron capture cross sections and resonance integrals of 138Ba(n, γ)139Ba and 141Pr(n, γ)142Pr were measured by activation method using an isotopic Am-Be neutron source. The estimations were with respect to that of 55Mn(n, γ)56Mn and 197Au(n, γ)198Au reference monitors. The measured thermal-capture cross section of 138 Ba with respect to 55 Mn is 0.410±0.023 b and with respect to 197 Au is 0.386±0.019 b. The measured thermal-capture cross section of 141 Pr with respect to 55 Mn is 11.36±1.29 b and with respect to 197 Au is 10.43±1.14 b. The resonance integrals for 138 Ba are 0.380±0.033 b (55 Mn) and 0.364±0.027 b (197 Au) and for 141 Pr are 21.05±2.88 b (55 Mn) and 15.27±1.87 b (197 Au). The comparison between the present measurements and various reported values are discussed. The cross sections corresponding to the selected isotopes are measured using an Am-Be source facility for the first time.

  2. Mechanism of ternary breakup in the reaction {sup 197}Au+{sup 197}Au at 15A MeV

    SciTech Connect

    Tian Junlong; Wu Xizhen; Li Zhuxia; Zhao Kai; Zhang Yingxun; Li Xian; Yan Shiwei

    2010-11-15

    The mechanism of the ternary breakup of the very heavy system {sup 197}Au+{sup 197}Au at an energy of 15A MeV has been studied by using the improved quantum molecular dynamics model. The calculation results reproduce the characteristic features in ternary breakup events explored in a series of experiments; i.e., the masses of three fragments are comparable in size and the very fast, nearly collinear breakup of the colliding system is dominant in the ternary breakup events. Further, the evolution of the time scales of different ternary reaction modes and the behavior of mass distributions of three fragments with impact parameters are studied. The time evolution of the configurations of the composite reaction systems is also studied. We find that for most of the ternary breakup events with the features found in the experiments, the configuration of the composite system has two-preformed-neck shape. The study shows that those ternary breakup events having the characteristic features found in the experiments happen at relatively small impact parameter reactions, but not at peripheral reactions. The ternary breakup reaction at peripheral reactions belongs to binary breakup with a neck emission.

  3. Target rapidity baryon distributions in {sup 28}Si + {sup 197}Au and {sup 197}Au + {sup 197}Au collisions at 14.6 and 11.7 A{center_dot}GeV/c

    SciTech Connect

    Sangster, T.C.; Costales, J.B.; Namboodiri, M.N.; E802 Collaboration

    1993-02-25

    Proton and deuteron kinetic energy spectra have been measured at target rapidities for both minimum bias and central collisions of 14.6 A{center_dot}GeV/c {sup 28}Si and 11.7 A{center_dot}GeV/c {sup 197}Au beams with a {sup 197}Au target. The spectra were measured from a low energy threshold of approximately E{sub kin}=35 MeV to well over 200 MeV for laboratory angles of 50{degree} to 130{degree} ({vert_bar}{eta}{vert_bar} {le}0.76). The acceptance-corrected spectra have been fit over a limited range of kinetic energies using a Boltzmann distribution. The integrated yields and the inverse slope parameters are presented as a function of centrality for the {sup 28}Si + {sup 197}Au reaction and as a function of trigger for the {sup 197}Au + {sup 197}Au reaction. These quantities are also compared with the proton spectra generated using both the ARC and RQMD codes.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. Neutron scattering measurements in {sup 197}Au from 850 keV to 2.0 MeV

    SciTech Connect

    O`Connor, M.; Chen, J.; Egan, J.J.

    1995-10-01

    Differential elastic and inelastic neutron scattering cross-sections for low lying levels in {sup 197}Au have been measured for incident neutron energies of 1.0 MeV, 1.5 MeV and 2.0 MeV. In addition, the total neutron cross sections in {sup 197}Au was measured from 850 keV to 1.5 MeV. For both experiments the UML 5.5 MV Van-de-Graaff accelerator with a Mobley post acceleration compression system, produced subnanosecond proton pulses which generated neutrons via the {sup 7}Li(p,n) {sup 7}Be reaction.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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

  17. {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.

  18. New approximations to the energy dependences of the total cross sections for the proton-induced fission of {sup 197}Au, {sup 203}Tl, {sup nat}Pb, and {sup 209}Bi nuclei

    SciTech Connect

    Vaishnene, L. A.; Vovchenko, V. G.; Gavrikov, Yu. A.; Murzin, V. I.; Polyakov, V. V.; Tverskoi, M. G.; Fedorov, O. Ya.; Chestnov, Yu. A. Shvedchikov, A. V.; Shchetkovskii, A. I.

    2011-01-15

    The total cross sections for {sup 197}Au and {sup 203}Tl fission induced by protons of energy varied from about 200 to 1000 MeV with a step of about 100 MeV are measured. New approximations to the energy dependences of the cross sections for the proton-induced fission of {sup 197}Au, {sup 203}Tl, natPb, and {sup 209}Bi nuclei are presented and discussed. For all of these nuclei, exponential functions are used as approximations.

  19. 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.

  20. 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.

  1. 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

  2. Hyperfine splitting of the 2s1/2 and 2p1/2 levels in Li- and be-like ions of (59)(141) Pr.

    PubMed

    Beiersdorfer, P; Träbert, E; Brown, G V; Clementson, J; Thorn, D B; Chen, M H; Cheng, K T; Sapirstein, J

    2014-06-13

    High-resolution spectroscopy of the 2s(1/2)-2p(1/2) transition in the extreme ultraviolet region is shown to resolve the level splitting induced by the nuclear magnetic field of both the 2s(1/2) and the 2p(1/2) levels in lithiumlike (141)Pr(56+) and of the 2s(1/2)2p(1/2) (3)P(1) level in berylliumlike (141)Pr(55+). The (141)Pr ions are an ideal test of this measurement approach because their energy levels are known well from first principles and are unaffected by small energy contributions from QED and nuclear magnetization effects. The accuracy attained in the measured 196.5 ± 1.2 meV 2s(1/2) splitting is more than an order of magnitude better than that achieved before using crystal spectroscopy of the 2s(1/2)-2p(3/2) x-ray transition and at the level needed to implement a proposed scheme for disentangling the contributions from QED and nuclear magnetization effects in higher-Z ions, such as (209)Bi.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. 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

  11. 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}

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. Systematics of central heavy ion collisions in the 1A GeV regime

    NASA Astrophysics Data System (ADS)

    Reisdorf, W.; Andronic, A.; Averbeck, R.; Benabderrahmane, M. L.; Hartmann, O. N.; Herrmann, N.; Hildenbrand, K. D.; Kang, T. I.; Kim, Y. J.; Kiš, M.; Koczoń, P.; Kress, T.; Leifels, Y.; Merschmeyer, M.; Piasecki, K.; Schüttauf, A.; Stockmeier, M.; Barret, V.; Basrak, Z.; Bastid, N.; Čaplar, R.; Crochet, P.; Dupieux, P.; Dželalija, M.; Fodor, Z.; Gasik, P.; Grishkin, Y.; Hong, B.; Kecskemeti, J.; Kirejczyk, M.; Korolija, M.; Kotte, R.; Lebedev, A.; Lopez, X.; Matulewicz, T.; Neubert, W.; Petrovici, M.; Rami, F.; Ryu, M. S.; Seres, Z.; Sikora, B.; Sim, K. S.; Simion, V.; Siwek-Wilczyńska, K.; Smolyankin, V.; Stoicea, G.; Tymiński, Z.; Wiśniewski, K.; Wohlfarth, D.; Xiao, Z. G.; Xu, H. S.; Yushmanov, I.; Zhilin, A.; FOPI Collaboration

    2010-12-01

    Using the large acceptance apparatus FOPI, we study central collisions in the reactions (energies in A GeV are given in parentheses): 40Ca + 40Ca (0.4, 0.6, 0.8, 1.0, 1.5, 1.93), 58Ni + 58Ni (0.15, 0.25, 0.4), 96Ru + 96Ru (0.4, 1.0, 1.5), 96Zr + 96Zr (0.4, 1.0, 1.5), 129Xe + CsI (0.15, 0.25, 0.4), 197Au + 197Au (0.09, 0.12, 0.15, 0.25, 0.4, 0.6, 0.8, 1.0, 1.2, 1.5). The observables include cluster multiplicities, longitudinal and transverse rapidity distributions and stopping, and radial flow. The data are compared to earlier data where possible and to transport model simulations.

  18. Ultra Heavy Ion Collector (UHIC)

    NASA Technical Reports Server (NTRS)

    Stone, E. C.

    1997-01-01

    The purpose of this final report is to study the propagation of heavy nuclei in cosmic radiation. Topics include: Mass Distributions of Fragments from the Interactions of 600 MeV/n Silver Nuclei; Charge-pickup by Heavy Relativistic Nuclei; Fragmentation and Propagation Heavy UH Cosmic Ray Nuclei; Nuclear Fragmentation Parameters Needed for Interpretation of Observed Fluxes of UH Cosmic Ray Nuclei; Fragmentation and Electromagnetic Dissociation of 10.6 GeV/nucleon (197) Au Nuclei; Nuclear Interaction Cross Sections for UltraHeavy Nuclei; The Charge-Changing Fragmentation of 10.6 GeV/nucleon 197 Au Nuclei; Fragmentation Cross Sections of Relativistic 84/36 Kr and 109/47 Ag Nuclei in Targets from Hydrogen to Lead; Mission Concept for the Study of Ultraheavy Galactic Cosmic Rays; and Propagation of the Heaviest UH - Cosmic Ray Nuclei.

  19. 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.

  20. 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.

  1. 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.

  2. Hydrogen Interaction with Metal Halides: the Nuclear Quadrupole Coupling Constant of Gold in the {p}{-H}_2{-AuCl} Complex and Trends in the Other Hydrogen-Coinage Metal Halide Interactions

    NASA Astrophysics Data System (ADS)

    Obenchain, Daniel A.; Grubbs, G. S. Grubbs, Ii; Pickett, Herbert M.; Novick, Stewart E.

    2013-06-01

    The rotational spectrum of p-H_2-AuCl has been measured using a laser ablation equipped FTMW cavity spectrometer. The predicted structure, using a 60 electron core potential and an aug-cc-pVQZ at the MP2 level of theory, shows that H_2 has an r_e = 0.91Å. A predicted value for the eQq(χ_{aa}) of gold required a semi-empirical method using the results of previous AuCl complexes in the gas phase. Transitions have been measured across multiple J levels, and have been used to determine the rotational constants, centrifugal distortion constants, and nuclear quadrupole coupling constants of multiple isotopologues. The o-H_2-AuCl has also been observed. While the monomer value of the eQq of ^{197}Au was determined to be 9.63112(13) MHz in ^{197}Au^{35}Cl, we observed a significant change in the eQq of ^{197}Au in p-H_2-^{197}Au^{35}Cl to a value of -817.9983(36) MHz [0.02728556(12) cm^{-1}], giving rise to a Au hyperfine component splittings of approximately 220 MHz [0.007 cm^{-1}] and suggesting a change in electronic structure with the interaction of H_2. We will present a summary of the hydrogen-coinage metal halide talks given at this conference, including trends in eQq and hydrogen metal halide dissociation energies. D. Figgen, G. Rauhut, M. Dolh, H. Stoll J. Chem. Phys. 311(2005) 227. K. A. Peterson, C. Puzzarini, Theor. Chem. Acc. 114 (2005) 283. C. J. Evans, C. L. Gerry J. Mol. Spectrosc. 203 (2000) 105.

  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. 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.

  5. 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).

  6. 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.

  7. Fission studies with 140 MeV {alpha} particles

    SciTech Connect

    Buttkewitz, A.; Duhm, H. H.; Strauss, W.; Goldenbaum, F.; Machner, H.

    2009-09-15

    Binary fission induced by 140 MeV {alpha} particles has been measured for {sup nat}Ag, {sup 139}La, {sup 165}Ho, and {sup 197}Au targets. The measured quantities are the total kinetic energies, fragment masses, and fission cross sections. The results are compared with other data and systematics. A minimum of the fission probability in the vicinity Z{sup 2}/A=24 is observed.

  8. 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.

  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. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. Fractional processes and nuclear disassembly in very-heavy-ion collisions in the Fermi energy regime

    SciTech Connect

    Schroeder, W.U.

    1991-01-01

    Exclusive measurements of charged products and neutrons were performed for the reactions {sup 197}Au + (29 MeV/u) {sup 208}Pb and {sup 209}Bi + (28.2 MeV/u) {sup 136}Xe. The multiplicities of neutrons and charged particles are found to indicate collision impact parameters with different sensitivities. Characteristic correlations observed between massive products and light particles suggest the dominance of the damped-reaction mechanism in the Fermi energy domain. For central collisions, massive fragments are no longer observed, and a considerable fraction of the mass of the system is found disassembled into light particles and clusters. 75 refs., 19 figs.

  17. Experimental measurements with Monte Carlo corrections and theoretical calculations of neutron inelastic scattering cross section of 115In

    NASA Astrophysics Data System (ADS)

    Wang, Chao; Xiao, Jun; Luo, Xiaobing

    2016-10-01

    The neutron inelastic scattering cross section of 115In has been measured by the activation technique at neutron energies of 2.95, 3.94, and 5.24 MeV with the neutron capture cross sections of 197Au as an internal standard. The effects of multiple scattering and flux attenuation were corrected using the Monte Carlo code GEANT4. Based on the experimental values, the 115In neutron inelastic scattering cross sections data were theoretically calculated between the 1 and 15 MeV with the TALYS software code, the theoretical results of this study are in reasonable agreement with the available experimental results.

  18. 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.

  19. Comparison of fast cascade plus statistical models for heavy ion induced multifragmentation reactions

    NASA Astrophysics Data System (ADS)

    Mustafa, M. G.; Blann, M.; Peilert, G.; Botvina, A.

    1994-05-01

    We consider the reaction 36Ar+197Au at incident 36Ar energies of 35, 50, 80, and 110A MeV, comparing calculations of precompound decay using the Boltzmann master equation (BME) and quantum molecular dynamics (QMD) models. We then estimate quasiequilibrated nuclei and excitations using the BME, and use these values as input into statistical multifragmentation models. For the latter we compare sequential binary decay as an extension of the Weisskopf-Ewing evaporation model, and a simultaneous multifragmentation for an expanded low density gas. The exclusive multiplicities predicted by these models are compared with experimental results.

  20. Is the Coulomb sum rule violated in nuclei?

    NASA Astrophysics Data System (ADS)

    Morgenstern, J.; Meziani, Z.-E.

    2001-08-01

    Guided by the experimental confirmation of the validity of the Effective Momentum Approximation (EMA) in quasi-elastic scattering off nuclei, we have re-examined the extraction of the longitudinal and transverse response functions in medium-weight and heavy nuclei. In the EMA we have performed a Rosenbluth separation of the available world data on 40Ca, 48Ca, 56Fe, 197Au, 208Pb and 238U. We find that the longitudinal response function for these nuclei is "quenched" and that the Coulomb sum is not saturated, at odds with claims in the literature.

  1. Systematics of azimuthal asymmetries in heavy ion collisions in the 1A GeV regime

    NASA Astrophysics Data System (ADS)

    Reisdorf, W.; Leifels, Y.; Andronic, A.; Averbeck, R.; Barret, V.; Basrak, Z.; Bastid, N.; Benabderrahmane, M. L.; Čaplar, R.; Crochet, P.; Dupieux, P.; Dželalija, M.; Fodor, Z.; Gasik, P.; Grishkin, Y.; Hartmann, O. N.; Herrmann, N.; Hildenbrand, K. D.; Hong, B.; Kang, T. I.; Kecskemeti, J.; Kim, Y. J.; Kirejczyk, M.; Kiš, M.; Koczoń, P.; Korolija, M.; Kotte, R.; Kress, T.; Lebedev, A.; Lopez, X.; Matulewicz, T.; Merschmeyer, M.; Neubert, W.; Petrovici, M.; Piasecki, K.; Rami, F.; Ryu, M. S.; Schüttauf, A.; Seres, Z.; Sikora, B.; Sim, K. S.; Simion, V.; Siwek-Wilczyńska, K.; Smolyankin, V.; Stockmeier, M.; Stoicea, G.; Tymiński, Z.; Wiśniewski, K.; Wohlfarth, D.; Xiao, Z. G.; Xu, H. S.; Yushmanov, I.; Zhilin, A.; FOPI Collaboration

    2012-02-01

    Using the large acceptance apparatus FOPI, we study central and semi-central collisions in the reactions (energies in A GeV are given in parentheses): 40Ca + 40Ca (0.4, 0.6, 0.8, 1.0, 1.5, 1.93), 58Ni + 58Ni (0.15, 0.25, 0.4), 96Ru + 96Ru (0.4, 1.0, 1.5), 96Zr + 96Zr (0.4, 1.0, 1.5), 129Xe + CsI (0.15, 0.25, 0.4), 197Au + 197Au (0.09, 0.12, 0.15, 0.25, 0.4, 0.6, 0.8, 1.0, 1.2, 1.5). The observables include directed and elliptic flow. The data are compared to earlier data where possible and to transport model simulations. A stiff nuclear equation of state is found to be incompatible with the data. Evidence for extra-repulsion of neutrons in compressed asymmetric matter is found.

  2. Measurement of the fusion probability, PCN, for hot fusion reactions

    NASA Astrophysics Data System (ADS)

    Yanez, R.; Loveland, W.; Barrett, J. S.; Yao, L.; Back, B. B.; Zhu, S.; Khoo, T. L.

    2013-07-01

    Background: The cross section for forming a heavy evaporation residue in fusion reactions depends on the capture cross section, the fusion probability, PCN, i.e., the probability that the projectile-target system will evolve inside the fission saddle point to form a completely fused system rather than reseparating (quasifission), and the survival of the completely fused system against fission. PCN is the least known of these quantities.Purpose: We want to determine PCN for the reactions of 101.2 MeV 18O, 147.3 MeV 26Mg, 170.9 MeV 30Si, and 195.3 MeV 36S with 197Au.Methods: We measured the fission fragment angular distributions for these reactions and used the formalism of Back to deduce the fusion-fission and quasifission cross sections. From these quantities we deduced PCN for each reaction.Results: The values of PCN for the reactions of 101.2 MeV 18O, 147.3 MeV 26Mg, 170.9 MeV 30Si, and 195.3 MeV 36S with 197Au are 0.66, 1.00, 0.06, and 0.13, respectively.Conclusions: The new measured values of PCN agree roughly with the semiempirical systematic dependence of PCN upon fissility for excited nuclei.

  3. 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.

  4. Ultraviolet laser spectroscopy of the neutron-deficient bismuth isotopes

    NASA Astrophysics Data System (ADS)

    Xu, Fei

    1997-12-01

    The isotope shifts and nuclear moments of the neutron deficient bismuth isotopes 201-204Bi have been measured at Stony Brook with a highly sensitive gas cell technique. The isotopes were populated with the nuclear reactions 197Au(10B,6n)201Po and 197Au(11B,xn)208-xPo, with boron beams from the SUNY Stony Brook tandem-linac accelerator. The bismuth samples that accumulated from the Po decay were evaporated from the target material and illuminated with 1-2mW of 306.7nm radiation from an intra-cavity frequency doubled ring dye laser. By measuring and analyzing the fluorescence spectra of the bismuth isotopes, the isotope shifts and hyperfine constants were obtained and the nuclear moments were extracted. The systematic behaviour of isotope shifts of the neutron-deficient bismuth isotopes is discussed and compared with the Po, Pb, Tl and Fr isotope shifts. It was found that the isotonic and isotopic trends, around the doubly magic core of 208Pb, are nearly identical. This implies that the h9/2 valence proton in the bismuth isotopes does not have a strong effect on the deformation of the core.

  5. 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.

  6. 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.

  7. Monte Carlo simulation of the n_TOF Total Absorption Calorimeter

    NASA Astrophysics Data System (ADS)

    Guerrero, C.; Cano-Ott, D.; Mendoza, E.; Taín, J. L.; Algora, A.; Berthoumieux, E.; Colonna, N.; Domingo-Pardo, C.; González-Romero, E.; Heil, M.; Jordán, D.; Käppeler, F.; Lampoudis, C.; Martínez, T.; Massimi, C.; Plag, R.; n TOF Collaboration

    2012-04-01

    The n_TOF Total Absorption Calorimeter (TAC) is a 4π BaF2 segmented detector used at CERN for measuring neutron capture cross-sections of importance for the design of advanced nuclear reactors. This work presents the simulation code that has been developed in GEANT4 for the accurate determination of the detection efficiency of the TAC for neutron capture events. The code allows to calculate the efficiency of the TAC for every neutron capture state, as a function of energy, crystal multiplicity, and counting rate. The code includes all instrumental effects such as the single crystal detection threshold and energy resolution, finite size of the coincidence time window, and signal pile-up. The results from the simulation have been validated with experimental data for a large set of electromagnetic de-excitation patterns: β-decay of well known calibration sources, neutron capture reactions in light nuclei with well known level schemes like natTi, reference samples used in (n,γ) measurements like 197Au and experimental data from an actinide sample like 240Pu. The systematic uncertainty in the determination of the detection efficiency has been estimated for all the cases. As a representative example, the accuracy reached for the case of 197Au(n,γ) ranges between 0.5% and 2%, depending on the experimental and analysis conditions. Such a value matches the high accuracy required for the nuclear cross-section data needed in advanced reactor design.

  8. 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. 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.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. 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.

  2. 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.}

  3. 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.

  4. Thermal neutron radiative capture cross-section of 186W(n, γ)187W reaction

    NASA Astrophysics Data System (ADS)

    Tan, V. H.; Son, P. N.

    2016-06-01

    The thermal neutron radiative capture cross section for 186W(n, γ)187W reaction was measured by the activation method using the filtered neutron beam at the Dalat research reactor. An optimal composition of Si and Bi, in single crystal form, has been used as neutron filters to create the high-purity filtered neutron beam with Cadmium ratio of Rcd = 420 and peak energy En = 0.025 eV. The induced activities in the irradiated samples were measured by a high resolution HPGe digital gamma-ray spectrometer. The present result of cross section has been determined relatively to the reference value of the standard reaction 197Au(n, γ)198Au. The necessary correction factors for gamma-ray true coincidence summing, and thermal neutron self-shielding effects were taken into account in this experiment by Monte Carlo simulations.

  5. Precision Cross Section Measurement for the ^241Am(γ,n) Reaction at HIγS

    NASA Astrophysics Data System (ADS)

    Tonchev, A.; Hutcheson, A.; Howell, C. R.; Kwan, E.; Rusev, G.; Tornow, W.; Hammond, S.; Karwowski, H. J.; Huibregtse, C.; Kelley, J. H.; Vieira, D. L.; Wilhelmy, J. B.; Stoyer, M. A.

    2008-10-01

    The photodisintegration cross section on radioactive ^241Am target has been measured for the first time using monoenergetic γ-ray beams from the HIγS facility. Induced activity from ^240Am produced via the (γ,n) reaction was measured by the activation technique using high resolution HPGe detectors. The (γ,n) cross section was determined both by measuring the absolute γ-flux and by comparison to the ^197Au(γ,n) cross section used as a standard. In the following, we report new data for the excitation function of the ^241Am(γ,n ) reaction from near threshold to 16 MeV incident γ-ray energy and we compare the data with statistical nuclear-model calculations performed with the GNASH, EMPIRE, and TALYS codes.

  6. Photodisintegration Cross Section of 241Am

    NASA Astrophysics Data System (ADS)

    Tonchev, A. P.; Hammond, S.; Howell, C. R.; Huibregtse, C.; Hutcheson, A.; Karwowski, H. J.; Kelley, J. H.; Kwan, E.; Rusev, G.; Tornow, W.; Vieira, D. J.; Wilhelmy, J. B.

    2009-03-01

    The photodisintegration cross section of radioactive 241Am has been obtained for the first time using monoenergetic γ-ray beams from the HIγS facility. The induced activity of 240Am produced via the 241Am(γ,n) reaction in the γ-ray energy range from 9.5 to 16 MeV was measured by the activation technique utilizing high resolution HPGe detectors. The 241Am(γ,n) cross section was determined both by measuring the absolute γ-ray flux and by comparison to the 197Au(γ,n) and 58Ni(γ,n) cross section standards. The experimental data for the 241Am(γ,n) reaction in the giant dipole resonance energy region is compared with statistical nuclear-model calculations.

  7. γ decay from the quasicontinuum of Au,198197

    NASA Astrophysics Data System (ADS)

    Giacoppo, F.; Bello Garrote, F. L.; Bernstein, L. A.; Bleuel, D. L.; Firestone, R. B.; Görgen, A.; Guttormsen, M.; Hagen, T. W.; Klintefjord, M.; Koehler, P. E.; Larsen, A. C.; Nyhus, H. T.; Renstrøm, T.; Sahin, E.; Siem, S.; Tornyi, T.

    2015-05-01

    The average electromagnetic dipole response of levels in the quasicontinuum of Au,198197 has been measured using (3He,3He' ) and (d ,p ) reactions. The extracted γ -ray strength functions have been normalized according to three model assumptions for the nuclear spin distribution. An enhancement in the energy region Eγ=3.0 -6.5 MeV is observed for both isotopes. The E 1 component of such excess of strength is studied in detail for 198Au and is interpreted as the pygmy dipole resonance with an energy centroid of 5.9 (1 ) MeV and exhausts about 1 % of the total integrated strength. The pygmy dipole resonance is shown to have a significant impact on the calculated 197Au (n,γ ) 198Au cross section.

  8. Level densities and thermodynamical properties of Pt and Au isotopes

    NASA Astrophysics Data System (ADS)

    Giacoppo, F.; Bello Garrote, F. L.; Bernstein, L. A.; Bleuel, D. L.; Eriksen, T. K.; Firestone, R. B.; Görgen, A.; Guttormsen, M.; Hagen, T. W.; Kheswa, B. V.; Klintefjord, M.; Koehler, P. E.; Larsen, A. C.; Nyhus, H. T.; Renstrøm, T.; Sahin, E.; Siem, S.; Tornyi, T.

    2014-11-01

    The nuclear level densities of Pt-196194 and Au,198197 below the neutron separation energy have been measured using transfer and scattering reactions. All the level density distributions follow the constant-temperature description. Each group of isotopes is characterized by the same temperature above the energy threshold corresponding to the breaking of the first Cooper pair. A constant entropy excess Δ S =1.9 kB and 1.1 kB is observed in 195Pt and 198Au with respect to 196Pt and 197Au, respectively, giving information on the available single-particle level space for the last unpaired valence neutron. The breaking of nucleon Cooper pairs is revealed by sequential peaks in the microcanonical caloric curve.

  9. Modifications of gallium phosphide single crystals using slow highly charged ions and swift heavy ions

    NASA Astrophysics Data System (ADS)

    El-Said, A. S.; Wilhelm, R. A.; Heller, R.; Akhmadaliev, Sh.; Schumann, E.; Sorokin, M.; Facsko, S.; Trautmann, C.

    2016-09-01

    GaP single crystals were irradiated with slow highly charged ions (HCI) using 114 keV 129Xe(33-40)+ and with various swift heavy ions (SHI) of 30 MeV I9+ and 374 MeV-2.2 GeV 197Au25+. The irradiated surfaces were investigated by scanning force microscopy (SFM). The irradiations with SHI lead to nanohillocks protruding from the GaP surfaces, whereas no changes of the surface topography were observed after the irradiation with HCI. This result indicates that a potential energy above 38.5 keV is required for surface nanostructuring of GaP. In addition, strong coloration of the GaP crystals was observed after irradiation with SHI. The effect was stronger for higher energies. This was confirmed by measuring an increased extinction coefficient in the visible light region.

  10. 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.

  11. 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.

  12. 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.

  13. Calculations of the thermal and fast neutron fluxes in the Syrian miniature neutron source reactor using the MCNP-4C code.

    PubMed

    Khattab, K; Sulieman, I

    2009-04-01

    The MCNP-4C code, based on the probabilistic approach, was used to model the 3D configuration of the core of the Syrian miniature neutron source reactor (MNSR). The continuous energy neutron cross sections from the ENDF/B-VI library were used to calculate the thermal and fast neutron fluxes in the inner and outer irradiation sites of MNSR. The thermal fluxes in the MNSR inner irradiation sites were also measured experimentally by the multiple foil activation method ((197)Au (n, gamma) (198)Au and (59)Co (n, gamma) (60)Co). The foils were irradiated simultaneously in each of the five MNSR inner irradiation sites to measure the thermal neutron flux and the epithermal index in each site. The calculated and measured results agree well.

  14. 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.

  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. Heavy-ion versus {sup 3}He/{sup 4}He fusion-fission reactions: Angular momentum dependence of dissipation in nuclear fission

    SciTech Connect

    Ye, W.

    2011-09-15

    The stochastic Langevin model is employed to study dissipation properties in fission in the {sup 16}O + {sup 181}Ta {yields}{sup 197}Tl system by analyzing prescission neutron yields measured in this reaction. It has been found that the {sup 197}Tl nuclei undergo fission that is not in accordance with the standard Bohr-Wheeler statistical theory. A detailed comparison with previously published work in which fission excitation functions measured in {sup 3,4}He + {sup 197}Au {yields}{sup 200,201}Tl are shown to be in excellent agreement with the fission width formula predicted by the traditional models of nuclear fission suggests that nuclear dissipation strength may have an angular momentum dependence in addition to the known deformation and temperature dependence. Implications for the basic understanding of the observed abnormal rise in prescission particles at high energy and the need for further experimental confirmations are discussed.

  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. 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.

  19. 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

  20. Exploring multifragmentation with a 4{pi} detector: Xe-induced reactions at E{sub beam} = 60 MeV/nucleon

    SciTech Connect

    Skulski, W.; Tso, K.; Colonna, N.

    1994-01-01

    The reactions {sup 129}Xe + {sup 27}Al, {sup nat}Cu, {sup 89}Y, {sup 165}Ho and {sup 197}Au at 60 MeV/nucleon were investigated with the combination of a high-resolution forward array of Si-Si-plastic telescopes and a high-efficiency phoswich ball. The projectile-like primary source was reconstructed. Its parallel velocity component is strongly correlated with the observed multiplicity and hence with dissipation. At high multiplicity, large fragments still show a projectile-like and target-like components in their parallel velocity distributions. A further sub-division of highly dissipative events into binary-like and non binary-like subclasses has been performed by applying an additional experimental selection of the orientation of the event in momentum space.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. EY-EXAFS and Mössbauer spectroscopy of the Au/Si interface

    NASA Astrophysics Data System (ADS)

    Sawicki, J. A.; Hitchcock, A. P.; Tyliszcak, T.

    1989-06-01

    The Au-Si interface [1] plays a significant role in high speed VLSI electronic devices. However, the structure of this interface and particularly the formation and properties of gold silicides are not yet well established. In this work thin (3-50 μm/cm2) gold layers deposited on or implanted in (at doses from 1015 up to 7×1016/cm2) Si(111) single crytals, as well as gold diffused into Si through thermal or laser annealing, have been studied by Au L3 EXAFS with electron-yield detection (EY-EXAFS), and by conversion electron Mossbauer spectroscopy (CEMS) of the 77.3 γ-rays in 197Au. EY-EXAFS and CEMS probe local structure in a complementary fashion with depth sensitivities which are similar to the depth of diffused and ion implanted interfaces. Thus the combination of these tecniques is particularly useful for studies of implanted and deposited thin films.

  6. 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).

  7. 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.

  8. 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.

  9. 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.

  10. 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

  11. 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.

  12. 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.

  13. Calorimetric low temperature detectors for mass identification of heavy ions

    NASA Astrophysics Data System (ADS)

    Kraft, S.; Bleile, A.; Egelhof, P.; Golser, R.; Kisselev, O.; Kutschera, W.; Liechtenstein, V.; Meier, H. J.; Priller, A.; Shrivastava, A.; Steier, P.; Vockenhuber, C.; Weber, M.

    2002-02-01

    The energy sensitive detection of heavy ions with calorimetric low temperature detectors (CLTDs) is investigated for the energy range E=0.1-1 MeV/u, commonly used for accelerator mass spectrometry (AMS). Such measurements complement earlier investigations [1, 2] at higher energies (E=5-300 MeV/u) where an energy resolution of ΔE/E=1-2×10-3 was obtained for various ion species. The detectors used consist of sapphire absorbers and superconducting transition edge thermometers operated at T~1.5 K. They were irradiated with various heavy ion beams (13C, 197Au, 238U) provided by the VERA tandem accelerator in Vienna, Austria. An energy resolution of ΔE/E=5-6×10-3 has been obtained even for heaviest ions like 197Au and 238U at E=0.1-0.3 MeV/u, thereby exceeding the resolution of conventional semiconductor detectors in this energy range by at least one order of magnitude. In addition, no evidence for pulse height defects has been observed. With the achieved performance, the present CLTDs bear a large potential for applications in various fields of heavy ion research. Of special interest is isotope mass identification via combined energy and time-of-flight (TOF) measurement. In present test measurements, including a standard TOF spectrometer, a clear separation of the isotopes 206Pb and 208Pb at E~0.1 MeV/u has been obtained. Such a detection scheme may in future provide substantial background suppression for AMS measurements. .

  14. 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.

  15. (Studies of target fragmentation in intermediate energy, relativistic and ultra-relativistic nuclear collisions)

    SciTech Connect

    Loveland, W.D.

    1991-08-01

    The work described herein is part of a project involving the study of low energy (< 10 MeV/A), intermediate energy (10--100 MeV/A) and relativistic (> 250 MeV/A) heavy ion reactions. In the low energy regime, we published a monograph on the properties of the heaviest elements and used that publication as a basis for making a set of best'' semi-empirical predictions of heavy element decay properties. The intermediate energy research effort focussed upon the completion of studies already begun and the initiation of a number of new experiments. In our study of a interaction of 21 MeV/nucleon {sup 129}Xe with {sup 197}Au, we compared the characteristics of the observed deep inelastic phenomena with various models of dissipative reactions and found significant discrepancies between observations and predictions. These discrepancies seemed to be caused by an improper treatment of pre-equilibrium in the early stages of the collision. In our study of the relativistic interaction of 400 MeV/nucleon {sup 12}C with {sup 197}Au, we reported the first direct physical measurement of the properties of the spallation residues from a nucleus-nucleus collision. We found the residue energies to be much lower than those predicted by the intranuclear cascade model, indicating some substantial modifications of that model are needed. But, we also found, indications of significant, non-zero values of the residue transverse momentum, a finding that calls into question the interpretation of a number of radiochemical recoil studies of the kinematics of high energy reactions. A program of performing numerical simulations of intermediate and high energy nuclear collisions using the QMD model was initiated.

  16. [Studies of target fragmentation in intermediate energy, relativistic and ultra-relativistic nuclear collisions]. Nuclear chemistry progress report, August 1, 1990--August 1, 1991

    SciTech Connect

    Loveland, W.D.

    1991-08-01

    The work described herein is part of a project involving the study of low energy (< 10 MeV/A), intermediate energy (10--100 MeV/A) and relativistic (> 250 MeV/A) heavy ion reactions. In the low energy regime, we published a monograph on the properties of the heaviest elements and used that publication as a basis for making a set of ``best`` semi-empirical predictions of heavy element decay properties. The intermediate energy research effort focussed upon the completion of studies already begun and the initiation of a number of new experiments. In our study of a interaction of 21 MeV/nucleon {sup 129}Xe with {sup 197}Au, we compared the characteristics of the observed deep inelastic phenomena with various models of dissipative reactions and found significant discrepancies between observations and predictions. These discrepancies seemed to be caused by an improper treatment of pre-equilibrium in the early stages of the collision. In our study of the relativistic interaction of 400 MeV/nucleon {sup 12}C with {sup 197}Au, we reported the first direct physical measurement of the properties of the spallation residues from a nucleus-nucleus collision. We found the residue energies to be much lower than those predicted by the intranuclear cascade model, indicating some substantial modifications of that model are needed. But, we also found, indications of significant, non-zero values of the residue transverse momentum, a finding that calls into question the interpretation of a number of radiochemical recoil studies of the kinematics of high energy reactions. A program of performing numerical simulations of intermediate and high energy nuclear collisions using the QMD model was initiated.

  17. Measurement of thermal neutron cross-sections and resonance integrals for 164Dy(n,γ) 165Dy and 180Hf(n,γ) 181Hf reactions

    NASA Astrophysics Data System (ADS)

    Cho, Hyun-Je; Kobayashi, Katsuhei; Yamamoto, Shuji; Seo, Kyung-Won; Hwang, Han Yull; Nha, Sang Kyun; Ko, Seung Kook

    2001-04-01

    The thermal neutron cross-sections for the 164Dy(n,γ) 165Dy and the 180Hf(n,γ) 181Hf reactions have been measured by the activation method at the heavy water thermal neutron facility of the Kyoto University Reactor, KUR. The results measured at 0.0253 eV are 2656±98 b for the 164Dy(n,γ) 165Dy reaction and 13.04±0.47 b for the 180Hf(n,γ) 181Hf reaction, respectively. The results have been obtained relative to the reference value of 98.65±0.09 b for the 197Au(n,γ) 198Au reaction. For dysprosium, most of the experimental data and the evaluated ones in ENDF/B-VI and JEF-2.2 are in good agreement with the present value. For hafnium, the previous measurements and the evaluated ones in ENDF/B-VI and JENDL-3.2 are in good agreement with the present result. The resonance integrals for the 164Dy(n,γ) 165Dy and the 180Hf(n,γ) 181Hf reactions have also been measured relative to the reference value of 1550±28 b for the 197Au(n,γ) 198Au reaction using a 1/ E standard neutron spectrum field of the Kinki University Reactor, UTR-KINKI. The present resonance integral for the 164Dy(n,γ) 165Dy reaction is 649±24 b, and the existing experimental and the evaluated data are distributed from 335 to 820 b. The present result for the 180Hf(n,γ) 181Hf reaction is 32.4±1.2 b, and most of the previous measurements and the evaluated values are close to the present measurement. Gryntakis et al. reported the resonance integrals for both reactions, whose results were also in good agreement with the measurements.

  18. Dipole strength distributions in stable odd-mass nuclei in the vicinity of the N=82 isotones

    NASA Astrophysics Data System (ADS)

    Scheck, Marcus

    2006-10-01

    The low-lying dipole strength distributions in the odd-mass nuclei ^135Ba, ^137Ba, ^139La and ^141Pr were studied in nuclear resonance fluorescence (NRF) experiments performed at the Stuttgart Dynamitron facility. experiments used bremsstrahlung beams with endpoint energies of 4.1 MeV. The spin selective NRF reaction allowed the excitation of states through dipole transitions, up to 4 MeV. A special focus is the fragmented E1-strength of transitions connecting the ground state to states of the [2^+ 3^-] particle/hole coupling. The summed strength of the odd-mass nuclei is compared with the E1-strength of the [2^+ 3^-]1^- two-phonon states of the neighboring even-even core nuclei.

  19. 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.

  20. 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.

  1. 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.

  2. 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.

  3. Structural and mechanical characterization of ion-irradiated glassy polymeric carbon for TRISO fuel nuclear application

    NASA Astrophysics Data System (ADS)

    Abunaemeh, Malek; Seif, Mohamed; Elsamadicy, Abdalla; Ila, Daryush

    2012-08-01

    Tristructural isotropic (TRISO) fuel is considered as the fuel design of choice for the next generation of nuclear reactors (Generation IV). Its design consists of a fuel kernel of UO x coated with several layers having different functions. One of these functions is a containment shell/diffusion barrier for the fission fragments. Normally, the material of choice for this shell is pyrolytic carbon (PyC). The material does not offer a perfect barrier, due to its inherent crystalline structure, which is planar (like graphite) and therefore impossible to mold in one continuous sheet around the spherical fuel bead. Plane boundaries allow fragment diffusion at a much higher rate than through the plane. In this study, we investigate the possibility of replacing PyC with a different form of carbon, glassy polymeric carbon (GPC). We prepared samples of GPC and studied the evolution of their physical properties and structure as a function of the radiation environment that they were exposed to. The temperature at which the samples were held during irradiation was very similar to the Generation IV nuclear reactor (∼1000°C). During the fission of U235, the fission fragment mass distribution has two maxima around 98 and 137 amu, which would best correspond to elements Rb and Cs, respectively. However, both ions are hard to produce from our SNICS ion source at the Center for Irradiation of Materials; therefore, we used 107Ag and 197Au as best replacements. The irradiation sessions consisted in various fluences of 5 MeV Ag, and 5 MeV Au. For elemental sample analysis, we used transmission electron microscopy. For mechanical analysis, we used nano-indentation. It is of prime importance to measure the penetration of the implanted 107Ag.and 197Au and the evolution of mechanical properties of GPC irradiated with these ions. A procedure for manufacturing GPC with analysis is presented. This will show how the GPC structure differs as the temperature that it is prepared at increases

  4. Monte Carlo simulation of the NaI(Tl) detector response to measure gold activated foils

    NASA Astrophysics Data System (ADS)

    Amgarou, K.; Domingo, C.; Bouassoule, T.; Fernández, F.

    2009-09-01

    This work deals with the implementation of a NaI(Tl) detector for the assessment of the specific saturation activities of pure gold foils after neutron irradiation. These gold foils can be placed in the centre of a set of polyethylene spheres with different diameters. This configuration, known as a passive Bonner sphere system, is suitable to measure neutron spectra normally extended over a wide energy range containing up to 11 decades (from thermal to a few MeV), at places where the neutron field is very intense, high frequency pulsed or where it is mixed with an important high-energy photon component. The MCNPX code was used to evaluate the NaI(Tl) responses to different incident photon energies in terms of pulse-height distributions. An experimental validation of the calculated NaI(Tl) responses, using certified standard sources at a given measurement arrangement, indicates that MCNPX is a valid tool for routine calibration and benchmarking studies of this detector. A good agreement is found between the measured pulse-height distributions of the certified standard sources and those obtained from MCNPX simulations. As a preliminary application, a bare disc Au foil was directly exposed to a Bremsstrahlung photon beam at the isocentre of an 18 MV medical LINAC, in order to test the suitability of this activation material to measure the photo-neutrons generated in such facility. Two differentiated main photo-peaks, arising from 196Au and 198Au predominant γ-ray emissions, were observed. The two isotopes are produced mainly by the photonuclear, 197Au(γ, n) 196Au, and radiative capture, 197Au( n, γ) 198Au, reactions of, respectively, high-energy photons and thermal neutrons on the gold foil. From the measured 198Au saturation activity, a rough estimation of (378 ± 68) × 10 4 cm -2 Gy -1 was derived for the thermal neutron flux within the LINAC treatment room. This value, although being very approximate, is comparable to those reported by other authors for similar

  5. 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.

  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. Excitation function shape and neutron spectrum of the 7Li(p ,n )7Be reaction near threshold

    NASA Astrophysics Data System (ADS)

    Martín-Hernández, Guido; Mastinu, Pierfrancesco; Maggiore, Mario; Pranovi, Lorenzo; Prete, Gianfranco; Praena, Javier; Capote-Noy, Roberto; Gramegna, Fabiana; Lombardi, Augusto; Maran, Luca; Scian, Carlo; Munaron, Enrico

    2016-09-01

    The forward-emitted low energy tail of the neutron spectrum generated by the 7Li(p ,n )7Be reaction on a thick target at a proton energy of 1893.6 keV was measured by time-of-flight spectroscopy. The measurement was performed at BELINA (Beam Line for Nuclear Astrophysics) of the Laboratori Nazionali di Legnaro. Using the reaction kinematics and the proton on lithium stopping power the shape of the excitation function is calculated from the measured neutron spectrum. Good agreement with two reported measurements was found. Our data, along with the previous measurements, are well reproduced by the Breit-Wigner single-resonance formula for s -wave particles. The differential yield of the reaction is calculated and the widely used neutron spectrum at a proton energy of 1912 keV was reproduced. Possible causes regarding part of the 6.5% discrepancy between the 197Au(n ,γ ) cross section measured at this energy by Ratynski and Kappeler [Phys. Rev. C 37, 595 (1988), 10.1103/PhysRevC.37.595] and the one obtained using the Evaluated Nuclear Data File version B-VII.1 are given.

  11. Theoretical study of effects of the entrance channel on the relative yield of complete fusion and quasifission in heavy-ion collisions within a dinuclear system approach

    NASA Astrophysics Data System (ADS)

    Soheyli, S.; Khanlari, M. Varasteh

    2016-09-01

    The relative yield of complete fusion and quasifission components for the 12C+204Pb , 19F+197Au , 30Si+186W , and 48Ca+168Er reactions which all lead to the compound nucleus 216Ra are analyzed to calculate the entrance channel effects by comparison of capture, complete fusion, and quasifission cross sections, emission barriers (Bfus*,Bq f ), as well as complete fusion probability estimated by statistical method within the framework of the dinuclear system model. The difference among complete fusion probabilities calculated by the dinuclear system model for different entrance channels can be explained by the hindrance to complete fusion due to the larger inner fusion barrier Bfus* for the transformation of the dinuclear system into a compound nucleus and the increase of the quasifission contribution due to the decreasing of the emission barrier Bq f of quasifission as a function of the angular momentum. Although these reactions with different entrance channels populate the same compound nucleus 216Ra at similar excitation energies, the model predicts the negligible quasifission probability for reactions having higher entrance channel mass asymmetry and the dominant decay channel is complete fission. For reactions induced by massive projectiles such as Si and Ca having lower entrance channel mass asymmetry, the quasifission component is dominant in the evolution of dinuclear system, and the fusion process is extremely hindered.

  12. 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.

  13. The determination of reactor neutron spectrum-averaged cross-sections in miniature neutron source reactor facility.

    PubMed

    Jonah, S A; Ibrahim, Y V; Akaho, E H K

    2008-10-01

    A comparator method based on the resonance integral of (197)Au(n,gamma)(198)Au reaction has been used to determine fast neutron spectrum-averaged cross-section data of some dosimetry reactions in a miniature neutron source reactor (MNSR) facility. Target materials of low- and medium-mass nuclei, which are of interest in reactor dosimetry and NAA were investigated. Irradiation was performed under Cd cover in an inner irradiation channel of the Nigeria Research Reactor-1 (NIRR-1) currently fueled with highly enriched uranium (HEU). Spectrum-averaged cross-section data were calculated on the basis of the epithermal neutron flux monitored by the Al-0.1%Au foil irradiated along with the target materials. Results of (n,p) reaction on (27)Al, (28)Si, (29)Si, (46)Ti, (47)Ti, (56)Fe, (58)Ni, and (n,alpha) reaction on (30)Si were found to be in good agreement with recommended data within standard deviation. However, data obtained for the (27)Al(n,alpha) (24)Na and (64)Zn (n,p) (64)Cu reactions using the Al-0.1%Au foil as the flux monitor for both the comparator approach and the conventional method are higher than recommended data from the literature by over 25%.

  14. 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.

  15. 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.

  16. 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.

  17. Photodisintegration of heavy nuclei in the energy region above the giant dipole resonance

    SciTech Connect

    Ermakov, A. N.; Ishkhanov, B. S.; Kapitonov, I. M.; Makarenko, I. V. Orlin, V. N.

    2010-05-15

    Experimental data on yields of multiparticle photonuclear reactions (involving the emission of up to seven neutrons from the nucleus involved) on {sup 197}Au, {sup 203,205}Tl, and {sup 209}Bi nuclei in the region extending from the giant dipole resonance to an energy of 67.7 MeV are presented. These data are compared with the results of modern theoretical calculations that take into account both the excitation of a giant dipole resonance (GDR) in a nucleus and the photodisintegration of quasideutrons (QD) in it. By and large, experimental data confirm the results of theoretical calculations-that is, only upon taking simultaneously into account both alternative photodisintegration mechanisms (GDR excitation and QD photodisintegration) can one describe these experimental data. The contribution of QD photodisintegration grows with increasing photon energy and neutron multiplicity and becomes dominant for reactions involving the emission of not less than five neutrons from the nucleus being considered. The integrated cross sections for the processes in question were estimated on the basis of simultaneously employing experimental yields of multinucleon photonuclear reactions and the respective cross-section shapes calculated theoretically.

  18. 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.

  19. 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.

  20. 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.

  1. Swift heavy ion track formation in Gd2Zr2-xTixO7 pyrochlore: Effect of electronic energy loss

    NASA Astrophysics Data System (ADS)

    Lang, Maik; Toulemonde, Marcel; Zhang, Jiaming; Zhang, Fuxiang; Tracy, Cameron L.; Lian, Jie; Wang, Zhongwu; Weber, William J.; Severin, Daniel; Bender, Markus; Trautmann, Christina; Ewing, Rodney C.

    2014-10-01

    The morphology of swift heavy ion tracks in the Gd2Zr2-xTixO7 pyrochlore system has been investigated as a function of the variation in chemical composition and electronic energy loss, dE/dx, over a range of energetic ions: 58Ni, 101Ru, 129Xe, 181Ta, 197Au, 208Pb, and 238U of 11.1 MeV/u specific energy. Bright-field transmission electron microscopy, synchrotron X-ray diffraction, and Raman spectroscopy reveal an increasing degree of amorphization with increasing Ti-content and dE/dx. The size and morphology of individual ion tracks in Gd2Ti2O7 were characterized by high-resolution transmission electron microscopy revealing a core-shell structure with an outer defect-fluorite dominated shell at low dE/dx to predominantly amorphous tracks at high dE/dx. Inelastic thermal-spike calculations have been used together with atomic-scale characterization of ion tracks in Gd2Ti2O7 by high resolution transmission electron microscopy to deduce critical energy densities for the complex core-shell morphologies induced by ions of different dE/dx.

  2. 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.

  3. Tracing the evolution of temperature in near Fermi energy heavy ion collisions

    SciTech Connect

    Wang, J.; Keutgen, T.; Hagel, K.; Ma, Y.G.; Murray, M.; Qin, L.; Botvina, A.; Kowalski, S.; Materna, T.; Natowitz, J. B.; Keksis, A.; Makeev, A.; Marie, N.; Martin, E.; Ruangma, A.; Shetty, D.V.; Souliotis, G.; Veselsky, M.; Winchester, E.M.; Yennello, S.J.

    2005-08-01

    The kinetic-energy variation of emitted light clusters has been employed as a clock to explore the time evolution of the temperature for thermalizing composite systems produced in the reactions of 26A, 35A, and 47A MeV {sup 64}Zn with {sup 58}Ni, {sup 92}Mo, and {sup 197}Au. For each system investigated, the double-isotope ratio temperature curve exhibits a high maximum apparent temperature, in the range of 10-25 MeV, at high ejectile velocity. These maximum values increase with increasing projectile energy and decrease with increasing target mass. The time at which the maximum in the temperature curve is reached ranges from 80 to 130 fm/c after contact. For each different target, the subsequent cooling curves for all three projectile energies are quite similar. Temperatures comparable with those of limiting temperature systematics are reached 30 to 40 fm/c after the times corresponding to the maxima, at a time when antisymmetrized molecular dynamics transport model calculations predict entry into the final evaporative or fragmentation stage of deexcitation of the hot composite systems. Evidence for the establishment of thermal and chemical equilibrium is discussed.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. Determination of 198Au X-rays emission probabilities.

    PubMed

    Moreira, D S; Koskinas, M F; Dias, M S; Yamazaki, I M

    2010-01-01

    This work describes the measurements of the K X-ray and gamma-ray emission probabilities per decay of (198)Au performed at the Nuclear Metrology Laboratory (LMN) at the IPEN, São Paulo. The radioactive sample was obtained by means of (197)Au(n, gamma)(198)Au reaction irradiating an Au foil in a thermal neutron flux near the core of the IPEN 3.5 MW research reactor. The activity of samples was determined in a 4pibeta-gamma coincidence system, setting the gamma window at the 411.80 keV total energy absorption peak. The same samples were measured in two different spectrometers: a HPGe planar spectrometer with Be window, suitable for measurements in the low energy range and a coaxial REGe spectrometer. Both spectrometers were previously calibrated in a well defined geometry by means of standard sources calibrated in a 4pibeta-gamma coincidence system. MCNP4C Monte Carlo code was used for simulating the REGe spectrometer calibration curve, and a new version of code ESQUEMA was adopted for simulating the detection processes in the coincidence system, in order to predict the efficiency extrapolation curve.

  9. 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.

  10. 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.

  11. Experiments with trapped radioactive ^210Fr

    NASA Astrophysics Data System (ADS)

    Simsarian, J. E.; Orozco, L. A.; Shi, W.; Sprouse, G. D.; Zhao, W. Z.

    1996-05-01

    Francium, the heaviest of alkali atoms, is an excellent system for studing parity non-conservation (PNC) in atoms because of its large atomic number. The lack of stable isotopes has made the study its atomic structure difficult. Some of the relevant energy levels necesary for a PNC measurement have not been observed. At the Stony Brook Superconducting LINAC we produce 1 × 10^6 ^210Fr/s in the reaction ^197Au(^18O,5n)^210Fr. The atoms are transported as ions to the vicinity of the trap where they are neutralized and enter a Magneto Optical Trap (MOT) in a glass cell. From the initial capture of about one thousand ^210Fr into a MOT (J. E. Simsarian, A. Ghosh, G. Gwinner, L. A. Orozco, G. D. Sprouse and P. A. Voytas (Preprint Dec. 12, 1995)) we have increased the number of atoms to the point where their fluorescence is visible in a CCD camera. The larger number of atoms permits experiments to study the atomic structure of francium, in particular the location of the 8S and 9S energy levels. The lifetime measurement of the 7P_3/2 will help test the theoretical understanding of its atomic structure. Work supported by a Precision Measurement Grant from NIST and by NSF.

  12. Experiments with trapped ^210Fr

    NASA Astrophysics Data System (ADS)

    Sprouse, G. D.; Orozco, L. A.; Shi, W.; Simsarian, J. E.; Zhao, W. Z.

    1996-05-01

    Francium, the heaviest of alkali atoms, is an excellent system for the study of weak interactions in atoms because of its large atomic number. It has been difficult to study its atomic structure in great detail since there are no stable isotopes and sufficient quantities have not been available. At the Stony Brook Superconducting LINAC we produce 1 × 10^6 ^210Fr/s in the reaction ^197Au(^18O,5n)^210Fr. The atoms are transported as ions to the vicinity of the trap where they are neutralized and enter the capturing region of a Magneto-Optical Trap (MOT). From the initial [1] capture of ^210Fr into a MOT we have increased the number of atoms to the point where their fluorescence is visible in a CCD camera. The large number of atoms permits the initiation of experiments to study the atomic structure of francium relevant for a parity non-conservation measurement, such as the location of the 8S and 9S electronic states. Work supported by a Precision Measurement Grant from NIST and by NSF. [1] P. A. Voytas, A. Ghosh, G. Gwinner, L. A. Orozco, J. E. Simsarian, G. D. Sprouse, Postdeadline paper APS NPD, Indiana, October 1995; J. E. Simsarian, A. Ghosh, G. Gwinner, L. A. Orozco, G. D. Sprouse and P. A. Voytas (Preprint Dec. 12, 1995).

  13. 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.

  14. 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.

  15. Determination of k0-factors of short-lived nuclides and application of k0-NAA to selected trace elements

    NASA Astrophysics Data System (ADS)

    Acharya, R.; Holzbecher, J.; Chatt, A.

    2012-07-01

    As part of the standardization program of k0-based NAA (k0-NAA) methods at the Dalhousie University SLOWPOKE-2 reactor (DUSR) facility, the k0-factors of 15 analytically important short-lived nuclides (half-life <65 s) were determined with respect to gold (197Au). The elemental standards used were prepared mostly from their primary standard solutions. The samples were irradiated in both inner and outer pneumatic sites of the DUSR facility and counted using an HPGe-detector coupled to an ORTEC's digital gamma-ray spectrometer. The k0-factors determined using both inner and outer irradiation sites were found to be within ±5% with respect to either recommended or literature values in most cases. The Z-score values at 95% confidence level were found to be in the range of ±0.03-1.6. The k0-NAA method was applied to three different NIST standard reference materials (SRMs) and concentrations of six elements, namely Ag, F, Hf, Rb, Sc, and Se were determined using their short-lived nuclides. The concentrations of these elements were also determined by relative NAA method for comparison purposes.

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. Low-energy electromagnetic excitation strengths in 121Sb and 123Sb

    NASA Astrophysics Data System (ADS)

    Bryssinck, J.; Govor, L.; Bauwens, F.; Belic, D.; von Brentano, P.; de Frenne, D.; Fransen, C.; Gade, A.; Jacobs, E.; Kneissl, U.; Kohstall, C.; Linnemann, A.; Nord, A.; Pietralla, N.; Pitz, H. H.; Scheck, M.; Stedile, F.; Werner, V.

    2002-02-01

    Results are presented from nuclear resonance fluorescence experiments on the odd-mass nuclei 121Sb and 123Sb with Z=51. The improved sensitivity reached with the present NRF facility, installed at the 4.3 MV Dynamitron accelerator of the Stuttgart University, allowed the detection of huge numbers of weak photoexcitations in the stable Sb nuclei 121Sb (164 transitions) and 123Sb (83 transitions) in the energy range up to 4 MeV and 3.5 MeV, respectively. The data are compared to former results for odd-mass nuclei near the Z=50 and N=82 shell closures (117Sn, 139La, 141Pr, and 143Nd). In the odd-mass nuclei within the Z=50 region, a similar total amount of electromagnetic excitation strength below 4 MeV is found; however, in 121Sb and 123Sb (Z=51) this strength is much more fragmented than in 117Sn with a closed proton shell (Z=50).

  2. {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.

  3. 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.

  4. 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.

  5. 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.

  6. Internal radiotherapy techniques using radiolanthanide praseodymium-142: a review of production routes, brachytherapy, unsealed source therapy.

    PubMed

    Bakht, Mohamadreza K; Sadeghi, Mahdi

    2011-10-01

    Radionuclides of rare earth elements are gaining importance as emerging therapeutic agents in nuclear medicine. β(-)-particle emitter 142Pr [T (1/2) = 19.12 h, E(-)β = 2.162 MeV (96.3%), Eγ = 1575 keV (3.7%)] is one of the praseodymium-141 (100% abundant) radioisotopes. Production routes and therapy aspects of 142Pr will be reviewed in this paper. However, 142Pr produces via 141Pr(n, γ) 142Pr reaction by irradiation in a low-fluence reactor; 142Pr cyclotron produced, could be achievable. 142Pr due to its high β(-)-emission and low specific gamma γ-emission could not only be a therapeutic radionuclide, but also a suitable radionuclide in order for biodistribution studies. Internal radiotherapy using 142Pr can be classified into two sub-categories: (1) unsealed source therapy (UST), (2) brachytherapy. UST via 142Pr-HA and 142Pr-DTPA in order for radiosynovectomy have been proposed. In addition, 142Pr Glass seeds and 142Pr microspheres have been utilized for interstitial brachytherapy of prostate cancer and intraarterial brachytherapy of arteriovenous malformation, respectively.

  7. Can we improve the calculation of some excitation functions for deuteron-induced reactions?

    NASA Astrophysics Data System (ADS)

    Pierre Chau, Huu-Tai

    2015-12-01

    In this paper, we propose to use the CDCC* approach to calculate (d,p) excitation functions. Starting from the CDCC* results, we derive some (d,p) differential and integrated cross sections, then using a simple semi-phenomenological model, we calculate the excitation functions for this process. We compare our calculations with the experimental cross sections for the 27Al (d, p)28Al, 58Fe(d, p)59Fe, 59Co(d, p)60Co, 75As(d, p)76As, 81Br(d, p)82Br, 84Kr(d, p)85Kr, 86Kr(d, p)87Kr, 108Pd (d, p)109Pd, 140Ce(d, p)141Ce, 142Ce(d, p)143Ce, 141Pr(d, p)142Pr, 165Ho(d, p)166Ho, and 180Hf (d, p)181Hf reactions. We plan to include these cross sections into evaluations of d-induced reactions and this could be a first step for improving of the quality of the next decade cross sections libraries.

  8. 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.

  9. {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.

  10. 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.

  11. 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.

  12. (. mu. -1,1 prime -Bis(diphenylphosphine)ferrocene)bis(chlorogold): Synthesis, iron-57 and gold-197 Moessbauer spectroscopy, x-ray crystal structure, and antitumor activity

    SciTech Connect

    Hill, D.T.; Girard, G.R.; McCabe, F.L.; Johnson, R.K.; Eggleston, D.S. ); Stupik, P.D.; Zhang, J.H.; Reiff, W.M. )

    1989-09-06

    The title compound 2, Fdpp(AuCl){sub 2}, synthesized via the addition of Fdpp (1) to an aqueous solution of ((HOCH{sub 2}CH{sub 2}){sub 2}S)AuCl generated in situ by the thiodiglycol reduction of HAuCl{sub 4} showed a {sup 31}P({sup 1}H) NMR chemical shift at {delta} 27.39, which was downfield from that of 1 at {delta} -17.34 relative to (CH{sub 3}O)PO. The {sup 57}Fe Moessbauer spectrum of 2 is a doublet with parameters (IS = 0.50 mm/s relative to Fe, QS = 2.33 mm/s) similar to those of ferrocene. The {sup 197}Au Moessbauer spectrum of 2 is an asymmetric doublet (QS = 6.93 mm/s) with an IS of 3.81 mm/s relative to Au metal. Fdpp(AuCl){sub 2} crystallized in space group P{bar 1} with lattice constants a = 16.192 (4) {angstrom}, b = 16.921 (4) {angstrom}, and c = 10.878 (5) {angstrom} with Z = 3. Two crystallographically independent molecules, A and B, were observed in the structure of 2 with a chloroform solvate molecule per 1.5 formula units of the gold complex. For A, the P atoms are 180{degree} opposed and the rings exactly staggered, while in B the P atoms are 150{degree} apart and the rings are partially staggered. The P-Au-Cl linkage is nearly linear, and the bond distances fall within normal ranges. Evaluation in an ip P388 leukemia mouse model showed 1 and 2 to have only marginal activity with an increased life span (ILS) relative to untreated controls of 30% at a maximally tolerated dose (MTD) of 231 {mu}mol/kg and 40% ILS at 4 {mu}mol/kg, respectively. 27 refs., 4 figs., 3 tabs.

  13. 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

  14. 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.

  15. 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.

  16. 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.

  17. Preparation and investigation of diamond-like carbon stripper foils by filtered cathodic vacuum arc

    NASA Astrophysics Data System (ADS)

    Fan, Qiwen; Du, Yinghui; Zhang, Rong; Xu, Guoji

    2013-04-01

    Thin diamond-like carbon (DLC) stripper foils ˜5 μg/cm2 in thickness were produced and evaluated as heavy-ion strippers for the Beijing HI-13 Tandem Accelerator. The DLC layers ˜4 μg/cm2 in thickness were produced by the filtered cathodic vacuum arc technology onto glass slides coated with betaine-saccharose as releasing agent, which were previously covered with evaporated carbon layers ˜1 μg/cm2 in thickness by the controlled ac arc-discharge method. Irradiation lifetimes of the DLC stripper foils were tested using the heavy-ion beams at the terminal of the Beijing HI-13 Tandem Accelerator, and compared with those of the standard carbon stripper foils made by the combined dc and ac arc-discharge method. The measurements indicate that the DLC stripper foils outlast the standard combined dc and ac arc-discharge carbon stripper foils by a factor of at least 13 and 4for the 197Au- (˜9 MeV, ˜1 μA) and 63Cu- (˜9 MeV, ˜1 μA) ion beams, respectively. The structure and properties of the DLC foils deposited onto silicon substrates by the filtered cathodic vacuum arc technology were also evaluated and analyzed by scanning electron microscopy, Raman spectroscopy and X-ray photoelectron spectroscopy. The scanning electron microscopy images show that the DLC foils contain hardly droplets through the double 90° filters. The X-ray photoelectron spectrum indicates that sp3 bonds of the DLC foils exceed 70%. The integral intensity ratio of the D peak to the G peak (ID/IG) measured by the Raman spectroscopy is0.78.

  18. Gold and iron oxide associations under supergene conditions: An experimental approach

    NASA Astrophysics Data System (ADS)

    Greffié, Catherine; Benedetti, Marc F.; Parron, Claude; Amouric, Marc

    1996-05-01

    Abstract-The interaction of gold hydroxo-chloro complexes with iron oxides (ferrihydrites, goethites) during coprecipitation experiments is investigated. Chemical analyses of solids and solutions are coupled with a detailed characterization of the iron oxides with various methods, including X-ray diffraction, High Resolution Transmission Electron Microscopy (HRTEM), and Mössbauer spectroscopy. HCl solutions containing varying amounts of AuCl 4- and ferric nitrate were titrated to neutral or alkaline pH, resulting in the coprecipitation of gold and iron oxide phases (ferrihydrite or goethite). Reference titrations were performed in the absence of iron. Most of the gold was removed from solution in the presence of iron oxides whereas gold remained dissolved in the reference samples. In association with iron oxides two forms of gold have been identified by HRTEM and 197Au Mössbauer spectroscopy: metallic gold as well as chloro and/or hydroxo combined gold. This combined gold is in a trivalent state as the primary product which means that a reduction process is not a necessary step for the adsorption of gold species on iron oxides. Metallic gold characterized in these products by means of HRTEM consists mainly of colloids ranging from 3-60 nm in diameter embedded in the ferrihydrite matrix, as isolated particles or as particles associated with goethite laths. The smallest metallic gold particles detected would be almost invisible to classical observation techniques used for solid phases. In our experiments, oxidation-reduction reactions between Fe 2+ and Au 3+ are responsible for the presence of metallic gold observed on the iron phases. Photochemical reactions may also take part in the reduction process. Colloidal gold and gold complexes could be associated to the iron oxides by strong electrostatic interactions. Our results suggest that poorly ordered iron oxides are highly efficient in trapping gold from solutions thanks to their high surface area, and favor gold

  19. Range and etching behaviour of swift heavy ions in polymers

    NASA Astrophysics Data System (ADS)

    Singh, Lakhwant; Singh, Mohan; Samra, Kawaljeet Singh; Singh, Ravinder

    Aliphatic (CR-39) and aromatic (Lexan polycarbonate) polymers have been irradiated with a variety of heavy ions such as 58Ni, 93Nb, 132Xe, 139La, 197Au, 208Pb, 209Bi, and 238U having energy ranges of 5.60-8.00 MeV/n in order to study the range and etching kinetics of heavy ion tracksE The ion fluence (range ˜104-105 ions/cm2) was kept low to avoid the overlapping of etched tracks. The measured values of maximum etched track length were corrected due to bulk etching and over etching to obtain the actual range. The experimental results of range profiles were compared with those obtained by the most used procedures employed in obtaining range and stopping power. The range values of present ions have been computed using the semiempirical codes (SRIM-98, SRIM-2003.26, and LISE++:0-[Hub90]) in order to check their accuracy. The merits and demerits of the adopted formulations have been highlighted in the present work. It is observed that the range of heavy ions is greater in aromatic polymers (Lexan polycarbonate) as compared to the aliphatic polymers (CR-39) irradiated with similar ions having same incident energies. The SRIM-98 and SRIM2003.26 codes don't show any significant trend in deviations, however, LISE++:0-[Hub90] code provides overall good agreement with the experimental values. The ratio of track etch rate (along projectile trajectory) to the bulk etch rate has also been studied as a function of energy loss of heavy ions in these polymers.

  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. Structure alterations in microporous (Mg,Fe){sub 2}Al{sub 4}Si{sub 5}O{sub 18} crystals induced by energetic heavy-ion irradiation

    SciTech Connect

    Miletich, Ronald; Diego Gatta, G.; Redhammer, Guenther J.; Burchard, Michael; Meyer, Hans-Peter; Weikusat, Christian; Rotiroti, Nicola; Glasmacher, Ulrich A.; Trautmann, Christina; Neumann, Reinhard

    2010-10-15

    The microporous framework structure of (Mg{sub 1-x}Fe{sub x}){sub 2}Al{sub 4}Si{sub 5}O{sub 18} (=cordierite) has been subject to a comparative study on the effect of structural alterations originating from exposure to high-energy heavy ions. Oriented samples (with x=0.061, 0.122, and 0.170) were irradiated with swift {sup 124}Xe, {sup 197}Au and {sup 96}Ru ions with 11.1 MeV per nucleon energy and fluences of 1x10{sup 12} and 1x10{sup 13} ions/cm{sup 2}. Irradiated and non-irradiated samples were investigated by means of X-ray diffraction, Moessbauer spectroscopy and optical absorption spectroscopy. Structural investigations reveal an essentially unchanged Al,Si ordering, which appears to be unaffected by irradiation. The most remarkable macroscopic change is the ion-beam induced colouration, which could be assigned to electronic charge transfer transitions involving the Fe cations. Moessbauer spectra indicate an increased amount of {sup [4]}Fe{sup 3+} for the irradiated sample. The most noticeable structural alteration concerns irradiation-induced dehydration of extra-framework H{sub 2}O, which is accompanied by a reduction in the molar volume by {approx}0.2 vol%. - Graphical abstract: Cordierite single-crystal specimen showing the color change from pale blue (unirradiated) to a yellowish brown layer (irradiated) after exposure to relativistic {sup 124}Xe ions at a fluence of 1x10{sup 12} ions per cm{sup 2}.

  2. 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.

  3. The physics and detectors of the relativistic heavy ion collider (RHIC)

    SciTech Connect

    Hallman, T.J.

    1996-12-31

    In mid-1999 the Relativistic Heavy Ion Collider (RHIC) facility will begin accelerating {sup 197}Au nuclei to 100 A GeV. The effective temperature in the dense region of overlap when two nuclei collide nearly head on at this energy will reach 10{sup 12} degrees Kelvin. At this temperature a basic restructuring of matter is expected to occur, in which the quark and gluon constituents normally confined in hadronic matter form a chirally symmetric deconfined plasma. There are many signatures to help isolate evidence of a transition to a deconfined phase of matter. These include, for example: (1) strangeness saturation on a time scale too short to be accounted for by strangeness exchange interactions in a hadron gas, (2) color screening (vector meson suppression) in the plasma phase, (3) in-medium effects on the mass/lifetime of the vector mesons, (4) the observation of thermodynamic/chemical equilibrium, (5) thermal radiation from a hot plasma, (6) excess heavy flavor production, (7) a discontinuity or change in the correlation between energy density and entropy density, (8) the observation of a long hadronization time, (9) disoriented chiral condensate behavior (isospin or low pt correlations). Each of the RHIC detectors is optimized for the measurement of a number of the above signatures. It is therefore possible because of the very high particle densities at RHIC for these detectors to correlate multiple observables in a single event or in a sample of events. It will thus be possible to isolate events which exhibit correlated non-statistical fluctuations in several observables simultaneously. It will be possible at RHIC to make a self-consistent measurement of the initial conditions, and in particular the gluon distribution in the nucleus. This affords optimal use of perturbative QCD in providing guidance as to the evolution of the early stages of the collision. We review the design and capabilities of the four detectors at RHIC: BRAHMS, PHENIX, PHOBOS, and STAR.

  4. Direct determination of gold in rock samples using collision cell quadrupole ICP-MS.

    PubMed

    Yim, Seong A; Choi, Man Sik; Chae, Jung Sun

    2012-01-01

    This study investigated the determination of Au in rock samples using collision cell quadrupole inductively coupled plasma mass spectrometry (ICP-MS). It is essential to remove various interferents using a collision cell because polyatomic ions such as (181)Ta(16)O(+) and (180)Hf(16)O(1)H(+) can interfere with the direct determination of monoisotopic (197)Au when using ICP-MS. The addition of oxygen as a reaction gas removed isobaric interferents by transforming TaO(+) and HfOH(+) to TaO(2)(+), TaO(3)(+), and HfO(2)H(+), HfO(3)H(+), respectively, in the cell without significant Au(+) loss. The ion kinetic energy effect (IKEE) due to the potential difference between the plasma and the hexapole affected the reactions in the cell. Au and interfering ions were very sensitive to cell bias voltage (Vc) at constant plasma potential (Vp) and quadrupole bias voltage (Vq). Under the condition of hot plasma, the transmission of ions was promoted, and the maximum Au signal intensity was 50% greater than under normal conditions. At Vc > 7 V, TaO(+) ions were removed to background level. Optimized conditions for real sample analysis were obtained by introducing He as an additional collision gas in hot plasma. TaO(+) ions were removed to background level at He flow rates above 0.6 mL min(-1), and the Au signal remained high. The detection limit (three times the standard deviation of the blank) of this method was 3.06 pg g(-1). The results for reference materials (STM-1 and DGPM-1) and spiked samples showed good agreement between specified and measured concentrations.

  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. Muon spin relaxation and rotation studies of the filled skutterudite alloys praseodymium osmium ruthenium antimonide and praseodymium lanthanum osmium antimonide

    NASA Astrophysics Data System (ADS)

    Shu, Lei

    superconducting order parameter, since our ZF-muSR experiment detects nonzero spontaneous fields for Pr(Os0.9Ru0.1)4 Sb12 from measurement at ISIS, United Kingdom in different samples. Longitudinal-field muon spin relaxation experiments also have been carried out to elucidate the anomalous dynamic muon spin relaxation detected by ZF-muSR in those alloys. The dynamic muon relaxation found in the alloys appears to be due to 141Pr nuclear spin fluctuations, where the 141Pr moments are enhanced by hyperfine coupling to the Pr 3+ Van Vleck susceptibility.

  7. 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.

  8. Geochemical cycling and depositional patterns across the northeast region of the Greenland Ice Sheet as determined from trace element chemistry

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

    The Greenland Ice Sheet is both a repository of climate history and a major driver in Arctic and global climate. Between 1952 and 1955, Carl Benson led a series of traverses of the Greenland Ice Sheet (GIS), and characterized the GIS via mapping of the spatial distribution of annual net accumulation and classifying the diagenetic glacier facies (Benson, 1962). While polar ice sheets represent a unique archive of past atmospheric and climatic conditions, little information exists on large-scale geographical trends in trace element snow chemistry across GIS because of the remote, challenging location. In the spring of 2011, we undertook a 1120 km traverse of the GIS from Thule Air Base to Summit Station. Samples from 11 snow pits and 3 firn cores, dated by stable water isotopes, were analyzed and evaluated in seasonal resolution for their trace element content (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). Here, we present an initial analysis of the spatial gradients of these trace elements and an interpretation of how their depositional patterns characterize the GIS. The seasonal trends coupled with spatial variability of certain trace elements establish the behavior of specific aerosols (e.g. dust, sea salt, pollution), which will be useful in quantifying geochemical cycling across the GIS and comparing characterizations with results from Benson's traverses. Benson, CS. 1962. Stratigraphic studies in the snow and firn of the Greenland Ice Sheet. SIPRE Research Report, 70, 89 pp.

  9. 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.

  10. 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

  11. 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

  12. Anisotropic magnetic properties and giant magnetocaloric effect of single-crystal PrSi

    NASA Astrophysics Data System (ADS)

    Das, Pranab Kumar; Bhattacharyya, Amitava; Kulkarni, Ruta; Dhar, S. K.; Thamizhavel, A.

    2014-04-01

    A single crystal of PrSi was grown by the Czochralski method in a tetra-arc furnace. Powder x-ray diffraction of the as-grown crystal revealed that PrSi crystallizes in an FeB-type structure with space group Pnma (No. 62). The anisotropic magnetic properties were investigated by means of magnetic susceptibility, isothermal magnetization, electrical transport, and heat capacity measurements. Magnetic susceptibility data clearly indicate the ferromagnetic transition in PrSi with a TC of 52 K. The relative easy axis of magnetization was found to be the [010] direction. Heat capacity data confirm the bulk nature of the transition at 52 K and exhibit a huge anomaly at the transition. A sharp rise in the low-temperature heat capacity has been observed (below 5 K) which is attributed to the 141Pr nuclear Schottky heat capacity arising from the hyperfine field of the Pr moment. The estimated Pr magnetic moment 2.88 μB/Pr from the hyperfine splitting is in agreement with the saturation magnetization value obtained from the magnetization data measured at 2 K. From the crystal electric field analysis of the magnetic susceptibility, magnetization, and heat capacity data it is found that the degenerate J =4 Hund's rule derived state of the Pr3+ ion splits into nine singlets with an overall splitting of 284 K, the first excited singlet state separated by just 9 K from the ground state. The magnetic ordering in PrGe appears to be due to the exchange-generated admixture of low-lying crystal field levels. The magnetocaloric effect (MCE) has been investigated from magnetization data along all three principal crystallographic directions. The large magnetic entropy change, -ΔSM=22.2 J/kg K, and the relative cooling power, RCP = 460 J/kg, characteristic of the giant magnetocaloric effect are achieved near the transition temperature (TC = 52 K) for H = 70 kOe along [010]. Furthermore, the PrSi single crystal exhibits a giant MCE anisotropy.

  13. 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

    2016-03-22

    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

  14. 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

  15. 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.

  16. 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

  17. 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

  18. 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