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6. Coulomb excitation of the 242m Am isomer

Author

Hayes, A. B., Cline, D., Moody, K. J., Wu, C. Y., Becker, J. A., Carpenter, M. P., Carroll, J. J., Gohlke, D., Greene, J. P., Hecht, A. A., Janssens, R. V. F., Karamian, S. A., Lauritsen, T., Lister, C. J., Macri, R. A., Propri, R., Seweryniak, D., Wang, X., Wheeler, R., and Zhu, S.

Published
2007
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8. Proton elastic form factor ratios to $Q^2$=3.5 GeV$^2$ by polarization transfer

Author

Punjabi, V., Perdrisat, C.F., Aniol, K.A., Baker, F.T., Berthot, J., Bertin, P.Y., Bertozzi, W., Besson, A., Bimbot, L., Boeglin, W.U., Brash, E.J., Brown, D., Calarco, J.R., Cardman, L.S., Chai, Z., Chang, C.-C., Chen, J.-P., Chudakov, E., Churchwell, S., Cisbani, E., Dale, D.S., De Leo, R., Deur, A., Diederich, B., Domingo, J.J., Epstein, M.B., Ewell, L.A., G. Fissum, K., Fleck, A., Fonvieille, H., Frullani, S., Gao, J., Garibaldi, F., Gasparian, A., Gerstner, G., Gilad, S., Gilman, R., Glamazdin, A., Glashausser, C., Gomez, J., Gorbenko, V., Green, A., Hansen, J.-O., Howell, C.R., Huber, G.M., Iodice, M., De Jager, C.W., Jaminion, S., Jiang, X., Jones, M.K., Kahl, W., Kelly, J.J., Khayat, M., Kramer, L.H., Kumbartzki, G., Kuss, M., Lakuriki, E., Laveissière, G., LeRose, J.J., Liang, M., Lindgren, R.A., Liyanage, N., Lolos, G.J., Macri, R., Madey, R., Malov, S., Margaziotis, D.J., Markowitz, P., McCormick, K., McIntyre, J.I., Van Der Meer, R.L.J., Michaels, R., Milbrath, B.D., Mougey, J.Y., Nanda, S.K., Offermann, E.A.J.M., Papandreou, Z., Pentchev, L., Petratos, G.G., Piskunov, N.M., Pomatsalyuk, R.I., Prout, D.L., Quéméner, G., Ransome, R.D., Raue, B.A., Roblin, Y., Roche, R., Rutledge, G., Rutt, P.M., Saha, A., Saito, T., Sarty, A.J., Smith, T.P., Sorokin, P., Strauch, S., Suleiman, R., Takahashi, K., Templon, J.A., Todor, L., Ulmer, P.E., Urciuoli, G.M., Vernin, P., Vlahovic, B., Voskanyan, H., Wijesooriya, K., Wojtsekhowski, B.B., Woo, R.J., Xiong, F., Zainea, G.D., Zhou, Z.-L., Laboratoire de Physique Corpusculaire - Clermont-Ferrand (LPC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Institut de Physique Nucléaire d'Orsay (IPNO), Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique Subatomique et de Cosmologie (LPSC), Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Institut Polytechnique de Grenoble - Grenoble Institute of Technology-Centre National de la Recherche Scientifique (CNRS), HALL A, Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), and Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut Polytechnique de Grenoble - Grenoble Institute of Technology-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS)

Subjects
electron-proton scattering, protons, polarisation in elementary particle interactions, electromagnetic form factors, FOS: Physical sciences, 25.30.Bf, 13.40.Gp, 24.85.+p, Nuclear Experiment (nucl-ex), [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], Nuclear Experiment
Abstract

The ratio of the proton elastic electromagnetic form factors, $G_{Ep}/G_{Mp}$, was obtained by measuring $P_{t}$ and $P_{\ell}$, the transverse and longitudinal recoil proton polarization components, respectively, for the elastic $\vec e p \to e\vec p$ ~reaction in the four-momentum transfer squared range of 0.5 to 3.5 GeV$^2$. In the single-photon exchange approximation, the ratio $G_{Ep}/G_{Mp}$ is directly proportional to the ratio $P_t/P_{\ell}$. The simultaneous measurement of $P_{t}$ and $P_{\ell}$ in a polarimeter reduces systematic uncertainties. The results for the ratio $G_{Ep}/G_{Mp}$ show a systematic decrease with increasing $Q^2$, indicating for the first time a definite difference in the distribution of charge and magnetization in the proton. The data have been re-analyzed and systematic uncertainties have become significantly smaller than previously published results., Comment: 31 pages, 29 gfigures, submitted to Phys. Rev. C

Published
2005
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9. $G_{E_p}/G_{M_p}$ ratio by polarization transfer in $\vec{e}p\rightarrow e\vec{p}$

Author

Jones, M.K., Aniol, K.A., Baker, F.T., Berthot, J., Bertin, P.Y., Bertozzi, W., Besson, A., Bimbot, L., Boeglin, W.U., Brash, E.J., Brown, D., Calarco, J.R., Cardman, L.S., Chang, C.C., Chen, J.P., Chudakov, E., Churchwell, S., Cisbani, E., Dale, D.S., De Leo, R., Deur, A., Diederich, B., Domingo, J.J., Epstein, M.B., Ewell, L.A., Fissum, K.G., Fleck, A., Fonvieille, H., Frullani, S., Gao, J., Garibaldi, F., Gasparian, A., Gerstner, G., Gilad, S., Gilman, R., Glamazdin, A., Glashausser, C., Gomez, J., Gorbenko, V., Green, A., Hansen, J.O., Howell, C.R., Huber, G.M., Iodice, M., De Jager, C.W., Jaminion, S., Jiang, X., Kahl, W., Kelly, J.J., Khayat, M., Kramer, L.H., Kumbartzki, G., Kuss, M., Lakuriki, E., Laveissiere, G., Le Rose, J.J., Liang, M., Lindgren, R.A., Liyanage, N., Lolos, G.J., Macri, R., Madey, R., Malov, S., Margaziotis, D.J., Markowitz, P., McCormick, K., McIntyre, J.I., Vander Meer, R.L.J., Michaels, R., Milbrath, B.D., Mougey, J.Y., Nanda, S.K., Offermann, E.A.J.M., Papandreou, Z., Perdrisat, C.F., Petratos, G.G., Piskunov, N.M., Pomatsalyuk, R.I., Prout, D.L., Punjabi, V., Quéméner, G., Ransome, R.D., Raue, B.A., Roblin, Y., Roche, R., Rutledge, G., Rutt, P.M., Saha, A., Saito, T., Sarty, A.J., Smith, T.P., Sorokin, P., Strauch, S., Suleiman, R., Takahashi, K., Templon, J.A., Todor, L., Ulmer, P.E., Urciuoli, G.M., Vernin, P., Vlahovic, B., Voskanian, H., Wijesooriya, K., Wojtsekhowski, B.B., Woo, R.J., Xiong, F., Zainea, G.D., Zhou, Z.L., Laboratoire de Physique Corpusculaire - Clermont-Ferrand (LPC), Université Blaise Pascal - Clermont-Ferrand 2 (UBP)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Institut de Physique Nucléaire d'Orsay (IPNO), Centre National de la Recherche Scientifique (CNRS)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Paris-Sud - Paris 11 (UP11), Laboratoire de Physique Subatomique et de Cosmologie (LPSC), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut Polytechnique de Grenoble - Grenoble Institute of Technology-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS), HALL A, Université Paris-Sud - Paris 11 (UP11)-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), and Université Joseph Fourier - Grenoble 1 (UJF)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Institut Polytechnique de Grenoble - Grenoble Institute of Technology-Centre National de la Recherche Scientifique (CNRS)

Subjects
[PHYS.HEXP]Physics [physics]/High Energy Physics - Experiment [hep-ex], Physics::Accelerator Physics, Nuclear Experiment
Abstract

The ratio of the proton's elastic electromagnetic form factors was obtained by measuring the transverse and longitudinal polarizations of recoiling protons from the elastic scattering of polarized electrons with unpolarized protons. The ratio of the electric to magnetic form factor is proportional to the ratio of the transverse to longitudinal recoil polarizations. The ratio was measured over a range of four-momentum transfer squared between 0.5 and 3.5 GeV-squared. Simultaneous measurement of transverse and longitudinal polarizations in a polarimeter provides good control of the systematic uncertainty. The results for the ratio of the proton's electric to magnetic form factors show a systematic decrease with increasing four momentum squared, indicating for the first time a marked difference in the spatial distribution of charge and magnetization currents in the proton.

Published
2000
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12. MEASUREMENT OF FISSION PRODUCT YIELDS FROM FAST-NEUTRON-INDUCED FISSION.

Author

ARNOLD, C. W., BOND, E. M., BREDEWEG, T. A., FOWLER, M. M., MOODY, W. A., RUSEV, G., VIEIRA, D. J., WILHELMY, J. B., BECKER, J. A., HENDERSON, R., KENNEALLY, J., MACRI, R., MCNABB, D., RYAN, C., SHEETS, S., STOYER, M. A., TONCHEV, A. P., BHATIA, C., BHIKE, M., and FALLIN, B.

Subjects
FISSION products, NUCLEAR fission, FISSION neutrons, NUCLEAR physics, NEUTRON flux
Published
2013

13. FISSION MEASUREMENTS WITH DANCE.

Author

JANDEL, M., BREDEWEG, T. A., FOWLER, M. M., BOND, E. M., CHADWICK, M. B., CLEMENT, R. R., COUTURE, A., O'DONNELL, J. M., HAIGHT, R. C., KEKSIS, A. L., REIFARTH, R., RUNDBERG, R. S., ULLMANN, J. L., VIEIRA, D. J., WILHELMY, J. B., WOUTERS, J. M., AGVAANLUVSAN, U., DASHDORJ, D., MACRI, R. A., and PARKER, W. E.

Subjects
NEUTRON counters, NEUTRON capture, NUCLEAR fission, ACTINIDE elements, NEUTRON cross sections
Published
2008

14. The Radiative Strength Function Using the Neutron-Capture Reaction on 151,153Eu.

Author

Agvaanluvsan, U., Alpizar-Vicente, A., Becker, J. A., Becčvárř, F., Bredeweg, T. A., Clement, R., Esch, E., Folden III, C. M., Hatarik, R., Haight, R. C., Hoffman, D. C., Krticčka, M., Macri, R. A., Mitchell, G. E., Nitsche, H., O'Donnell, J. M., Parker, W., Reifarth, R., Rundberg, R. S., and Schwantes, J. M.

Subjects
NUCLIDES, NEUTRONS, NEUTRON sources, NEUTRON resonance, NUCLEAR physics
Abstract

Radiative strength functions in 152,154Eu nuclei for γ-ray energies below 6 MeV have been investigated. Neutron capture for incident neutron energies <1eV up to 100 keV has been measured for 151,153Eu targets. Properties of γ decay of neutron resonances in 152,154Eu nuclei are examined. The results of measurements are compared to outcome of simulation of γ cascades based on various models for the radiative strength function. Comparison between experimental data and simulation suggests existence of the low-energy resonance in these two nuclei. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

Published
2006
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16. Preparation of 235mU targets for 235U(n,n′)235mU cross section measurements.

Author

Bond, E. M., Glover, S., Vieira, D. J., Rundberg, R. S., Belier, G., Meot, V., Hynek, D., Jansen, Y., Becker, J., and Macri, R.

Subjects
NEUTRON cross sections, PARTICLES (Nuclear physics), NUCLEAR physics, DECAY schemes (Radioactivity), NUCLEAR chemistry
Abstract

This paper describes the preparation of samples for an experiment to measure the cross-section for 235U(n,n′)235mU in a fast fission spectrum of neutrons provided by a fast pulsed reactor/critical assembly. Samples of 235mU have been prepared for the calibration of the internal conversion electron detector that is used for the 235mU measurement. Two methods are described for the preparation of 235mU. The first method used a U-Pu chemical separation based on anion-exchange chromatography and the second method used an alpha recoil collection method. Thin, uniform samples of 235mU+235U were prepared for the experiment using electrodeposition. [ABSTRACT FROM AUTHOR]

Published
2008
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17. Coulomb excitation of the 242 m Am isomer.

Author

Hayes, A., Cline, D., Moody, K., Wu, C., Becker, J., Carpenter, M., Carroll, J., Gohlke, D., Greene, J., Hecht, A., Janssens, R., Karamian, S., Lauritsen, T., Lister, C., Macri, R., Propri, R., Seweryniak, D., Wang, X., Wheeler, R., and Zhu, S.

Abstract

The 242 m Am isomer, a well-known candidate for photodepopulation research, has been studied in this first ever Coulomb excitation of a nearly pure (≈98%) isomer target. Thirty new states, including a new rotational band built on a K π = 6− state, have been identified. Strong K-mixing results in nearly equal populations of the K π=5− and 6− states. Newly identified states have been assigned to the K π=3− rotational band, the lowest states of which are known to decay into the ground-state band. Implications regarding K-mixing and Coulomb excitation paths to the ground state are discussed. [ABSTRACT FROM AUTHOR]

Published
2007
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22. 241Am(n,γ) cross section in the neutron energy region between 0.02 eV and 300 keV.

Author

Jandel, M., Bredeweg, T. A., Bond, E. M., Chadwick, M. B., Clement, R. R., Couture, A., O' Donnell, J. M., Haight, R. C., Reifarth, R., Rundberg, R. S., Ullmann, J. L., Vieira, D. J., Wilhelmy, J. B., Wouters, J. M., Macri, R. A., Wu, C. Y., and Becker, J. A.

Subjects
RADIATIVE capture, GAMMA rays, RESONANCE, NEUTRON capture, CALORIMETRY, PARTICLES (Nuclear physics), NUCLEAR physics
Abstract

The Detector for Advanced Neutron Capture Experiments (DANCE) at Los Alamos National Laboratory (LANL) was used for a neutron capture cross section measurement on 241Am. The high granularity of the DANCE array (160 BaF2 detectors in a 4π geometry) enables an efficient detection of prompt gamma rays following neutron capture. The preliminary results on the 241Am(n,γ) cross section are presented from 0.02 eV to 300 keV. The cross section at thermal energy En = 0.0253 eV was determined to be 665±33 barns. Resonance parameters were obtained using the SAMMY7 fit to the measured cross section in the resonance region. Significant discrepancies were found between our results and data evaluations for the first three lowest lying resonances. The cross section for neutrons with En>l keV agrees well with the ENDF/B-VII.0 and JENDL-3.3 evaluations. [ABSTRACT FROM AUTHOR]

Published
2008
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23. Simultaneous measurement of (n,γ) and (n,fission) cross sections with the DANCE 4π BaF2 array.

Author

Bredeweg, T. A., Fowler, M. M., Becker, J. A., Bond, E. M., Chadwick, M. B., Clement, R. R. C., Esch, E.-I., Ethvignot, T., Granier, T., Hunt, L. F., Macri, R. A., O'Donnell, J. M., Rundberg, R. S., Schwantes, J. M., Ullmann, J. L., Vieira, D. J., Wilhelmy, J. B., Wouters, J. M., Wu, C.-Y., and Yurkon, J. E.

Subjects
PARTICLES (Nuclear physics), COLLISIONS (Nuclear physics), EINSTEIN-Podolsky-Rosen experiment, DIRECT energy conversion, NUCLEAR physics, NUCLEAR energy
Abstract

Neutron capture cross section measurements on many of the actinides are complicated by low-energy neutron-induced fission, which competes with neutron capture to varying degrees depending on the nuclide of interest. Measurements of neutron capture on 235U using the Detector for Advanced Neutron Capture Experiments (DANCE) have shown that we can partially resolve capture from fission events based on total photon calorimetry (i.e. total γ-ray energy and γ-ray multiplicity per event). The addition of a fission-tagging detector to the DANCE array will greatly improve our ability to separate these two competing processes so that improved neutron capture and (n,γ)/(n,fission) cross section ratio measurements can be obtained. The addition of a fission-tagging detector to the DANCE array will also provide a means to study several important issues associated with neutron-induced fission, including (n,fission) cross sections as a function of incident neutron energy, and total energy and multiplicity of prompt fission photons. We have focused on two detector designs with complementary capabilities, a parallel-plate avalanche counter and an array of solar cells. © 2006 American Institute of Physics [ABSTRACT FROM AUTHOR]

Published
2006
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25. Exploratory study of fission product yields of neutron-induced fission of 235U, 238U, and 239Pu at 8.9 MeV.

Author

Bhatia, C., Fallin, B. F., Gooden, M. E., Howell, C. R., Kelley, J. H., Tornow, W., Arnold, C. W., Bond, E., Bredeweg, T. A., Fowler, M. M., Moody, W., Rundberg, R. S., Rusev, G. Y., Vieira, D. J., Wilhelmy, J. B., Becker, J. A., Macri, R., Ryan, C., Sheets, S. A., and Stoyer, M. A.

Subjects
*URANIUM isotopes, *PLUTONIUM isotopes, *FISSION products, *URANIUM 238, *ACTINIDE elements, *NEUTRON beams, *MONOENERGETIC radiation
Abstract

Using dual-fission chambers each loaded with a thick (200-400-mg/cm²) actinide target of 235,238U or 239Pu and two thin (~10-100-μg/cm²) reference foils of the same actinide, the cumulative yields of fission products ranging from 92Sr to 147Nd have been measured at En = 8.9MeV. The ²H(d,n)³He reaction provided the quasimonoenergetic neutron beam. The experimental setup and methods used to determine the fission product yield (FPY) are described, and results for typically eight high-yield fission products are presented. Our FPYs for 235U(n,f), 238U(n,f), and 239Pu(n,f) at 8.9 MeV are compared with the existing data below 8 MeV from Glendenin et al. [Phys. Rev. C 24, 2600 (1981)], Nagy et al. [Phys. Rev. C 17, 163 (1978)], Gindler et al. [Phys. Rev. C 27, 2058 (1983)], and those of Mac Innes et al. [Nucl. Data Sheets 112, 3135 (2011)] and Laurec et al. [Nucl. Data Sheets 111, 2965 (2010)] at 14.5 and 14.7 MeV, respectively. This comparison indicates a negative slope for the energy dependence of most fission product yields obtained from 235U and 239Pu, whereas for 238U the slope issue remains unsettled. [ABSTRACT FROM AUTHOR]

Published
2015
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26. Integral cross section measurement of the 235U(n,n')235mU reaction in a pulsed reactor.

Author

Bélier, G., Bond, E. M., Vieira, D. J., Authier, N., Becker, J. A., Hyneck, D., Jacquet, X., Jansen, Y., Legendre, J., Macri, R., Méot, V., and Romain, P.

Subjects
*NUCLEAR cross sections, *PULSED reactors, *INELASTIC cross sections, *NUCLEAR decay by heavy ion emission, *NUCLEAR isomers, *RADIOCHEMISTRY, *IRRADIATION, *INELASTIC scattering
Abstract

The integral measurement of the neutron inelastic cross section leading to the 26-minute half-life 235mU isomer in a fission-like neutron spectrum is presented. The experiment has been performed at a pulsed reactor, where the internal conversion decay of the isomer was measured using a dedicated electron detector after activation. The sample preparation, efficiency measurement, irradiation, radiochemistry purification, and isomer decay measurement will be presented. We determined the integral cross section for the 235U(n,n')235mU reaction to be 1.00 ± 0.13 b. This result supports an evaluation performed with TALYS-1.4 code with respect to the isomer excitation as well as the total neutron inelastic scattering cross section. [ABSTRACT FROM AUTHOR]

Published
2015
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