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Your search keyword '"Ghelberg, S."' showing total 38 results
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38 results on '"Ghelberg, S."'

1. The 40Ca(alpha,gamma)44Ti reaction in the energy regime of supernova nucleosynthesis

Author

Nassar, H., Paul, M., Ahmad, I., Ben-Dov, Y., Caggiano, J., Ghelberg, S., Goriely, S., Greene, J. P., Hass, M., Heger, A., Heinz, A., Henderson, D. J., Janssens, R. V. F., Jiang, C. L., Kashiv, Y., Singh, B. S. Nara, Ofan, A., Pardo, R. C., Pennington, T., Rehm, K. E., Savard, G., Scott, R., and Vondrasek, R.

Subjects
Nuclear Experiment, Astrophysics
Abstract

The 44Ti(t1/2 = 59 y) nuclide, an important signature of supernova nucleosynthesis, has recently been observed as live radioactivity by gamma-ray astronomy from the Cas A remnant. We investigate in the laboratory the major 44Ti production reaction, 40Ca(alpha,gamma)44Ti (E_cm = 0.6-1.2 MeV/u), by direct off- line counting of 44Ti nuclei. The yield, significantly higher than inferred from previous experiments, is analyzed in terms of a statistical model using microscopic nuclear inputs. The associated stellar rate has important astrophysical consequences, increasing the calculated supernova 44Ti yield by a factor ~2 over previous estimates and bringing it closer to Cas A observations., Comment: To be published in Phys. Rev. lett., 4 pages, 1 table, 2 figures

Published
2005
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2. The stellar (n,gamma) cross section of 62Ni

Author

Nassar, H., Paul, M., Ahmad, I., Berkovits, D., Bettan, M., Collon, P., Dababneh, S., Ghelberg, S., Greene, J. P., Heger, A., Heil, M., Henderson, D. J., Jiang, C. L., Kaeppeler, F., Koivisto, H., O'Brien, S., Pardo, R. C., Patronis, N., Pennington, T., Plag, R., Rehm, K. E., Reifarth, R., Scott, R., Sinha, S., Tang, X., and Vondrasek, R.

Subjects
Nuclear Experiment
Abstract

The 62Ni(n,gamma)63Ni(t_1/2=100+-2 yrs) reaction plays an important role in the control of the flow path of the slow neutron-capture (s-) nucleosynthesis process. We have measured for the first time the total cross section of this reaction for a quasi-Maxwellian (kT = 25 keV) neutron flux. The measurement was performed by fast-neutron activation, combined with accelerator mass spectrometry to detect directly the 63Ni product nuclei. The experimental value of 28.4+-2.8 mb, fairly consistent with a recent theoretical estimate, affects the calculated net yield of 62Ni itself and the whole distribution of nuclei with 62

Published
2004
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3. Experimental Limit to Interstellar 244Pu Abundance

Author

Paul, M., Valenta, A., Ahmad, I., Berkovits, D., Bordeanu, C., Ghelberg, S., Hashimoto, Y., Hershkowitz, A., Jiang, S., Nakanishi, T., and Sakamoto, K.

Subjects
Astrophysics
Abstract

Short-lived nuclides, now extinct in the solar system, are expected to be present in the interstellar medium (ISM). Grains of ISM origin were recently discovered in the inner solar system and at Earth orbit and may accrete onto Earth after ablation in the atmosphere. A favorable matrix for detection of such extraterrestrial material is presented by deep open-sea sediments with very low sedimentation rates (0.8-3 mm/kyr). We report here on the measurement of Pu isotopic abundances in a 1-kg deep-sea dry sediment collected in 1992 in the North Pacific. Our measured value of (3+-3)x10^5 244Pu atoms in the Pu-separated fraction of the sample shows no excess over the expected stratospheric nuclear fallout content and under reasonable assumptions we derive a limit of 2x10^-11 g-244Pu/g-ISM for the abundance of 244Pu in ISM., Comment: 10 p, 1 fig, LateX(AASTeX) Accepted for publication in ApJL, aug 2, 2001

Published
2001
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7. Production and isobaric separation of 63Ni ions for determination of the 62Ni(n,γ) 63Ni reaction cross section at stellar temperatures

Author

Nassar, H., Ghelberg, S., Paul, M., Dababneh, S., Heil, M., Käppeler, F., Plag, R., Ahmad, I., Greene, J.P., Henderson, D.J., Jiang, C.L., Pardo, R.C., Pennington, T., Rehm, K.E., Scott, R., Sinha, S., Tang, X., Vondrasek, R., Koivisto, H., Berkovits, D., Bettan, M., Reifarth, R., Collon, P., O'Brien, S., and Patronis, N.

Published
2004
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9. Ca40(α,γ)Ti44 reaction in the energy regime of supernova nucleosynthesis

Author

Kashiv, Y., Pennington, T., Hass, M., Vondrasek, R., Heger, A., Heinz, A., Caggiano, J., Henderson, D.J., Janssens, R.V.F., Savard, G., Nassar, H., Paul, M., Ben-Dov, Y., Scott, R., Greene, J.P., Nara Singh, B.S., Ofan, A., Rehm, K.E., Pardo, R.C., Ghelberg, S., Goriely, S., Jiang, C.L., and Ahmad, I.

Abstract

The Ti44(t1/2=59yr) nuclide, an important signature of supernova nucleosynthesis, has recently been observed as live radioactivity by γ-ray astronomy from the Cas A remnant. We investigate in the laboratory the major Ti44 production reaction Ca40(α,γ)Ti44 (Ec.m.∼0.6-1.2MeV/u) by direct off-line counting of Ti44 nuclei. The yield, significantly higher than inferred from previous experiments, is analyzed in terms of a statistical model using microscopic nuclear inputs. The associated stellar rate has important astrophysical consequences, increasing the calculated supernova Ti44 yield by a factor ∼2 over previous estimates and bringing it closer to Cas A observations.

Published
2006
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10. Stellar (n,gamma) cross section of Ni-62

Author

Nassar, H., Paul, M., Ahmad, I., Berkovits, D., Bettan, M., Collon, P., Dababneh, S., Ghelberg, S., Greene, J. P., Heger, A., Heil, M., Henderson, D. J., Jiang, C. L., Kappeler, F., Koivisto, H., O'Brien, S., Pardo, R. C., Patronis, N., Pennington, T., Plag, R., Rehm, K. E., Reifarth, R., Scott, R., Sinha, S., Tang, X., and Vondrasek, R.

Subjects
separation, massive stars, ion-source, nucleosynthesis, capture, s-process
Abstract

The Ni-62(n,gamma)Ni-63(t(1/2) = 100 +/- 2 yr) reaction plays an important role in the control of the flow path of the slow neutron-capture (s) nucleosynthesis process. We have measured for the first time the total cross section of this reaction for a quasi-Maxwellian (kT = 25 keV) neutron flux. The measurement was performed by fast-neutron activation, combined with accelerator mass spectrometry to detect directly the Ni-63 product nuclei. The experimental value of 28.4 +/- 2.8 mb, fairly consistent with a recent calculation, affects the calculated net yield of Ni-62 itself and the whole distribution of nuclei with 62 < A < 90 produced by the weak s process in massive stars. Phys Rev Lett

Published
2005

11. Ca40(α,γ)Ti44 reaction in the energy regime of supernova nucleosynthesis

Author

Nassar, Hisham, Paul, Michael, Ahmad, Irshad, Ben-Dov, Yair, Caggiano, Jac, Ghelberg, S., Goriely, Stéphane, Greene, John P., Hass, Michael, Heger, Alexander, Heinz, Andreas, Henderson, Dale J., Janssens, Robert V. F., Jiang, Cheng-Lie, Kashiv, Yoav, Nara Singh, Bondili S., Ofan, Avishai, Pardo, Richard C., Pennington, Tad, Rehm, Karl E., Savard, Guy, Scott, Roger, Vondrasek, Richard C., Nassar, Hisham, Paul, Michael, Ahmad, Irshad, Ben-Dov, Yair, Caggiano, Jac, Ghelberg, S., Goriely, Stéphane, Greene, John P., Hass, Michael, Heger, Alexander, Heinz, Andreas, Henderson, Dale J., Janssens, Robert V. F., Jiang, Cheng-Lie, Kashiv, Yoav, Nara Singh, Bondili S., Ofan, Avishai, Pardo, Richard C., Pennington, Tad, Rehm, Karl E., Savard, Guy, Scott, Roger, and Vondrasek, Richard C.

Abstract

SCOPUS: ar.j, info:eu-repo/semantics/published

Published
2006

13. Ca40(α,γ)Ti44Reaction in the Energy Regime of Supernova Nucleosynthesis

Author

Nassar, H., primary, Paul, M., additional, Ahmad, I., additional, Ben-Dov, Y., additional, Caggiano, J., additional, Ghelberg, S., additional, Goriely, S., additional, Greene, J. P., additional, Hass, M., additional, Heger, A., additional, Heinz, A., additional, Henderson, D. J., additional, Janssens, R. V. F., additional, Jiang, C. L., additional, Kashiv, Y., additional, Nara Singh, B. S., additional, Ofan, A., additional, Pardo, R. C., additional, Pennington, T., additional, Rehm, K. E., additional, Savard, G., additional, Scott, R., additional, and Vondrasek, R., additional

Published
2006
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15. Stellar(n,γ)Cross Section ofNi62

Author

Nassar, H., primary, Paul, M., additional, Ahmad, I., additional, Berkovits, D., additional, Bettan, M., additional, Collon, P., additional, Dababneh, S., additional, Ghelberg, S., additional, Greene, J. P., additional, Heger, A., additional, Heil, M., additional, Henderson, D. J., additional, Jiang, C. L., additional, Käppeler, F., additional, Koivisto, H., additional, O’Brien, S., additional, Pardo, R. C., additional, Patronis, N., additional, Pennington, T., additional, Plag, R., additional, Rehm, K. E., additional, Reifarth, R., additional, Scott, R., additional, Sinha, S., additional, Tang, X., additional, and Vondrasek, R., additional

Published
2005
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16. Production and isobaric separation of 63Ni ions for determination of the 62Ni(n,γ)63Ni reaction cross section at stellar temperatures

Author

Nassar, H., primary, Ghelberg, S., additional, Paul, M., additional, Dababneh, S., additional, Heil, M., additional, Käppeler, F., additional, Plag, R., additional, Ahmad, I., additional, Greene, J.P., additional, Henderson, D.J., additional, Jiang, C.L., additional, Pardo, R.C., additional, Pennington, T., additional, Rehm, K.E., additional, Scott, R., additional, Sinha, S., additional, Tang, X., additional, Vondrasek, R., additional, Koivisto, H., additional, Berkovits, D., additional, Bettan, M., additional, Reifarth, R., additional, Collon, P., additional, O'Brien, S., additional, and Patronis, N., additional

Published
2004
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18. Counting 44Ti nuclei from the 40Ca(α,γ)44Ti reaction

Author

Paul, M., primary, Feldstein, C., additional, Ahmad, I., additional, Berkovits, D., additional, Bordeanu, C., additional, Caggiano, J., additional, Ghelberg, S., additional, Goerres, J., additional, Greene, J., additional, Hass, M., additional, Heinz, A., additional, Henderson, D., additional, Hui, S.K., additional, Janssens, R.V.F., additional, Jiang, C.L., additional, Jiang, S., additional, Nirel, Y., additional, Pardo, R.C., additional, Pennington, T., additional, Rehm, K.E., additional, Savard, G., additional, Verri, G., additional, Vondrasek, R., additional, Wiedenhover, I., additional, and Wiescher, M., additional

Published
2003
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22. atom counting for nuclear astrophysics

Author

Hui, S.K., primary, Paul, M., additional, Berkovits, D., additional, Boaretto, E., additional, Ghelberg, S., additional, Hass, M., additional, Hershkowitz, A., additional, and Navon, E., additional

Published
2000
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30. An upper limit to interstellar 244Pu abundance as deduced from radiochemical search in deep-sea sediment: An account.

Author

Paul, M., Valenta, A., Ahmad, I., Berkovits, D., Bordeanu, C., Ghelberg, S., Hashimoto, Y., Hershkowitz, A., Jiang, S., Nakanishi, T., and Sakamoto, K.

Subjects
INTERSTELLAR medium, COSMIC abundances, PLUTONIUM isotopes, MARINE sediments, RADIOCHEMICAL research
Abstract

We report here a search for the “live” 244Pu in 1 kg deep-sea dry sediment collected in 1992 in the North Pacific. After a 546 day alpha-counting of a Pu fraction chemically separated from the alkaline-fused sediment sample at Kanazawa University, AMS analysis was performed at Hebrew University and Weizmann Institute. Only one count of 244Pu with no background ions was detected, indicating no excess over the expected stratospheric man-made fallout. A limit of 0.2 atoms of 244Pu cm−2·y−1 for extra terrestrial deposition was set under reasonable assumptions and it was then concluded from this result and the available data on interstellar medium (ISM) that the abundance of 244Pu in the ISM is less than 2·10−11 g 244Pu (g·ISM)−1. Implications of the present result are discussed. [ABSTRACT FROM AUTHOR]

Published
2007
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31. Study of the supernova nucleosynthesis 40Ca(α,γ)44Ti reaction: progress report

Author

Nassar, H., Paul, M., Ghelberg, S., Ofan, A., Trubnikov, N., Ben-Dov, Y., Hass, M., and Nara Singh, B.S.

Subjects
*NUCLEOSYNTHESIS, *COSMOCHEMISTRY, *SPACE sciences, *COSMIC abundances
Abstract

We report on a study of the α-capture reaction on 40Ca in the energy range relevant to supernova nucleosynthesis (T9 ∼ 0.8–3). The experiment measures the overall yield of 44Ti nuclei produced in an activation of a thick 4He target by a 40Ca beam. Preliminary results show a significantly stronger yield than observed in previous measurements in the range T9 ∼ 1.5–3. [Copyright &y& Elsevier]

Published
2005
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32. 40Ca(alpha, gamma)44Ti reaction in the energy regime of supernova nucleosynthesis.

Author

Nassar H, Paul M, Ahmad I, Ben-Dov Y, Caggiano J, Ghelberg S, Goriely S, Greene JP, Hass M, Heger A, Heinz A, Henderson DJ, Janssens RV, Jiang CL, Kashiv Y, Nara Singh BS, Ofan A, Pardo RC, Pennington T, Rehm KE, Savard G, Scott R, and Vondrasek R

Abstract

The 44Ti(t1/2=59 yr) nuclide, an important signature of supernova nucleosynthesis, has recently been observed as live radioactivity by gamma-ray astronomy from the Cas A remnant. We investigate in the laboratory the major 44Ti production reaction 40Ca(alpha, gamma)44Ti (Ec.m. approximately 0.6-1.2 MeV/u by direct off-line counting of 44Ti nuclei. The yield, significantly higher than inferred from previous experiments, is analyzed in terms of a statistical model using microscopic nuclear inputs. The associated stellar rate has important astrophysical consequences, increasing the calculated supernova 44Ti yield by a factor approximately 2 over previous estimates and bringing it closer to Cas A observations.

Published
2006
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33. Stellar (n,gamma) cross section of 62Ni.

Author

Nassar H, Paul M, Ahmad I, Berkovits D, Bettan M, Collon P, Dababneh S, Ghelberg S, Greene JP, Heger A, Heil M, Henderson DJ, Jiang CL, Käppeler F, Koivisto H, O'Brien S, Pardo RC, Patronis N, Pennington T, Plag R, Rehm KE, Reifarth R, Scott R, Sinha S, Tang X, and Vondrasek R

Abstract

The 62Ni(n,gamma)63Ni(t(1/2)=100+/-2 yr) reaction plays an important role in the control of the flow path of the slow neutron-capture (s) nucleosynthesis process. We have measured for the first time the total cross section of this reaction for a quasi-Maxwellian (kT=25 keV) neutron flux. The measurement was performed by fast-neutron activation, combined with accelerator mass spectrometry to detect directly the 63Ni product nuclei. The experimental value of 28.4+/-2.8 mb, fairly consistent with a recent calculation, affects the calculated net yield of 62Ni itself and the whole distribution of nuclei with 62

Published
2005
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34. [Research on the prolonged administration of some organochlorine pesticide substances (lindane, DDT) on laboratory white mice].

Author

Petrescu ST, Dobre V, Leibovici M, Petrescu Z, and Ghelberg SA

Subjects
Abnormalities, Drug-Induced, Adrenal Glands drug effects, Animals, Ascorbic Acid metabolism, Body Weight drug effects, Carcinogens, Female, Fetus drug effects, Hematopoiesis drug effects, Liver drug effects, Metabolism drug effects, Mice, Neoplasms, Experimental chemically induced, Ovary drug effects, Reproduction drug effects, DDT toxicity, Hexachlorocyclohexane toxicity
Published
1974

38. [Effect of association of ascorbic acid with other vitamins on the level of ascorbinemia].

Author

Aizicovici H, Ghelberg SA, Freund S, Chiorpec E, and Dragan M

Subjects
Adolescent, Child, Drug Synergism, Female, Humans, Male, Niacinamide therapeutic use, Riboflavin therapeutic use, Stimulation, Chemical, Thiamine therapeutic use, Vitamin A therapeutic use, Vitamin D therapeutic use, Ascorbic Acid blood, Ascorbic Acid therapeutic use, Vitamins therapeutic use
Published
1969

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