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68 results on '"U. Greife"'

1. First inverse kinematics measurement of key resonances in the 22Ne(p,γ)23Na reaction at stellar temperatures

Author

A. Lennarz, M. Williams, A.M. Laird, U. Battino, A.A. Chen, D. Connolly, B. Davids, N. Esker, R. Garg, M. Gay, U. Greife, U. Hager, D. Hutcheon, J. José, M. Lovely, S. Lyons, A. Psaltis, J.E. Riley, A. Tattersall, and C. Ruiz

Subjects
Inverse kinematics measurements, Radiative capture reactions, Stellar nucleosynthesis, Physics, QC1-999
Abstract

In this Letter we report on the first inverse kinematics measurement of key resonances in the Ne22(p,γ)23Na reaction which forms part of the NeNa cycle, and is relevant for 23Na synthesis in asymptotic giant branch (AGB) stars. An anti-correlation in O and Na abundances is seen across all well-studied globular clusters (GC), however, reaction-rate uncertainties limit the precision as to which stellar evolution models can reproduce the observed isotopic abundance patterns. Given the importance of GC observations in testing stellar evolution models and their dependence on NeNa reaction rates, it is critical that the nuclear physics uncertainties on the origin of 23Na be addressed. We present results of direct strengths measurements of four key resonances in Ne22(p,γ)23Na at Ec.m. = 149 keV, 181 keV, 248 keV and 458 keV. The strength of the important Ec.m. = 458 keV reference resonance has been determined independently of other resonance strengths for the first time with an associated strength of ωγ = 0.439(22) eV and with higher precision than previously reported. Our result deviates from the two most recently published results obtained from normal kinematics measurements performed by the LENA and LUNA collaborations but is in agreement with earlier measurements. The impact of our rate on the Na-pocket formation in AGB stars and its relation to the O-Na anti-correlation was assessed via network calculations. Further, the effect on isotopic abundances in CO and ONe novae ejecta with respect to pre-solar grains was investigated.

Published
2020
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2. A direct measurement of the 17O(α,γ)21Ne reaction in inverse kinematics and its impact on heavy element production

Author

M.P. Taggart, C. Akers, A.M. Laird, U. Hager, C. Ruiz, D.A. Hutcheon, M.A. Bentley, J.R. Brown, L. Buchmann, A.A. Chen, J. Chen, K.A. Chipps, A. Choplin, J.M. D'Auria, B. Davids, C. Davis, C.Aa. Diget, L. Erikson, J. Fallis, S.P. Fox, U. Frischknecht, B.R. Fulton, N. Galinski, U. Greife, R. Hirschi, D. Howell, L. Martin, D. Mountford, A.St.J. Murphy, D. Ottewell, M. Pignatari, S. Reeve, G. Ruprecht, S. Sjue, L. Veloce, and M. Williams

Subjects
Physics, QC1-999
Abstract

During the slow neutron capture process in massive stars, reactions on light elements can both produce and absorb neutrons thereby influencing the final heavy element abundances. At low metallicities, the high neutron capture rate of 16O can inhibit s-process nucleosynthesis unless the neutrons are recycled via the 17O(α,n)20Ne reaction. The efficiency of this neutron recycling is determined by competition between the 17O(α,n)20Ne and 17O(α,γ)21Ne reactions. While some experimental data are available on the former reaction, no data exist for the radiative capture channel at the relevant astrophysical energies.The 17O(α,γ)21Ne reaction has been studied directly using the DRAGON recoil separator at the TRIUMF Laboratory. The reaction cross section has been determined at energies between 0.6 and 1.6 MeV Ecm, reaching into the Gamow window for core helium burning for the first time. Resonance strengths for resonances at 0.63, 0.721, 0.81 and 1.122 MeV Ecm have been extracted. The experimentally based reaction rate calculated represents a lower limit, but suggests that significant s-process nucleosynthesis occurs in low metallicity massive stars.

Published
2019
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3. The first science result with the JENSA gas-jet target: Confirmation and study of a strong subthreshold F18(p,α)O15 resonance

Author

D.W. Bardayan, K.A. Chipps, S. Ahn, J.C. Blackmon, R.J. deBoer, U. Greife, K.L. Jones, A. Kontos, R.L. Kozub, L. Linhardt, B. Manning, M. Matoš, P.D. O'Malley, S. Ota, S.D. Pain, W.A. Peters, S.T. Pittman, A. Sachs, K.T. Schmitt, M.S. Smith, and P. Thompson

Subjects
Novae, Nucleosynthesis, Nuclear, Reactions, Physics, QC1-999
Abstract

The astrophysical F18(p,α)O15 rate determines, in large part, the extent to which the observable radioisotope 18F is produced in novae. This rate, however, has been extremely uncertain owing to the unknown properties of a strong subthreshold resonance and its possible interference with higher-lying resonances. The new Jet Experiments in Nuclear Structure and Astrophysics (JENSA) gas-jet target has been used for the first time to determine the spin of this important resonance and significantly reduce uncertainties in the F18(p,α)O15 rate.

Published
2015
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4. Design of a 400 kV deep underground, high detector efficiency, high target density, high beam intensity accelerator facility

Author

A. Lemut, M. Couder, D. Winklehner, U. Greife, A. Hodgkinson, D. Leitner, M. Leitner, J. S. Saba, P. A. Vetter, W. L. Waldron, and M. Wiescher

Subjects
Nuclear and particle physics. Atomic energy. Radioactivity, QC770-798
Abstract

Thermonuclear reaction cross sections of astrophysical interest decrease exponentially with energy, approaching the level of femtobarn or less at the Gamow window. Experimental investigations of such small reaction rates in laboratories at the earth’s surface are hampered by the cosmic-ray background into detectors. For such studies, Dakota Ion Accelerator for Nuclear Astrophysics, a deep underground, high detector efficiency, high target density, high beam intensity accelerator facility is being designed. We report on a 100 mA, 400 kV accelerator design. To take into account the beam space-charge effects, advanced three-dimensional transportation calculations have been performed. These highly realistic beam calculations demonstrate that high beam currents can be transported to a gas-jet target with a diameter of few millimeters.

Published
2011
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5. The NIFFTE project

Author

J., Ruz, M., Asner D., G., Baker R., J., Bundgaard, E., Burgett, M., Cunningham, J., Deaven, L., Duke D., U., Greife, S., Grimes, M., Heffner, T., Hill, D., Isenhower, L., Klay J., V., Kleinrath, N., Kornilov, B., Laptev A., W., Loveland, N., Masseyf T., R., Meharchand, H., Qu, S., Sangiorgio, B., Seilhan, L., Snyder, S., Stave, G., Tatishvili, T., Thornton R., F., Tovesson, D., Towell, S., Towell R., S., Watson, B., Wendt, and L, Wood

Subjects
Physics - Instrumentation and Detectors, Nuclear Experiment
Abstract

The Neutron Induced Fission Fragment Tracking Experiment (NIFFTE) is a double-sided Time Projection Chamber (TPC) with micromegas readout designed to measure the energy-dependent neutron-induced fission cross sections of the major and minor actinides with unprecedented accuracy. The NIFFTE project addresses the challenge of minimizing major sources of systematic uncertainties from previous fission chamber measurements such as: target and beam non-uniformities, misidentification of alpha and light charged particles as fission fragments, and uncertainties inherent to the reference standards used. In-beam tests of the NIFFTE TPC at the Los Alamos Neutron Science Center (LANSCE) started in 2010 and have continued in 2011, 2012 and 2013. An overview of the NIFFTE TPC status and performance at LANSCE will be presented., Comment: Prepared for JINST as proceeding of the MPGD13 Conference

Published
2013
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6. Stopping Force Analysis of 235U Elemental Fission Product Yields for E = 0.11–92.4 MeV

Author

M.E. Moore, J. Latta, L. Snyder, B.G. Fulsom, U. Greife, S.M. Lyons, L.S. Wood, D.L. Duke, M. Anastasiou, J.S. Barrett, N.S. Bowden, J. Bundgaard, R.J. Casperson, T. Classen, D.H. Dongwi, J. Gearhart, V. Geppert-Kleinrath, M. Haseman, M. Heffner, D. Higgins, J. King, J.L. Klay, W. Loveland, J.A. Magee, B. Manning, M.P. Mendenhall, M. Monterial, C. Prokop, S. Sangiorgio, B. Seilhan, F. Tovesson, R.S. Towell, and L. Yao

Subjects
Nuclear and High Energy Physics
Published
2022

10. Measurement of the normalized U238(n,f)/U235(n,f) cross section ratio from threshold to 30 MeV with the NIFFTE fission Time Projection Chamber

Author

D. Higgins, N. S. Bowden, N. Hertel, F. Tovesson, D. Hensle, L. Yao, B. Wendt, C. Brune, W. Younes, K. T. Schmitt, L. D. Isenhower, M. Heffner, J. Ruz, H. Qu, N. Walsh, U. Hager, T. Classen, J. Baker, E. Guardincerri, J. S. Barrett, J. King, S. Sangiorgio, A. B. Laptev, D. A. Cebra, S. Sharma, M. Lynch, B. Seilhan, V. Geppert-Kleinrath, W. S. Lynn, M. Cunningham, R. Meharchand, R. S. Towell, L. Wood, T. Hill, S. Stave, A. C. Tate, W. Loveland, G. Tatishvili, S. Grimes, T. N. Massey, L. Snyder, J. Bundgaard, B. Manning, J. L. Klay, U. Greife, S. Watson, J. A. Magee, J. Gearhart, D. M. Asner, I. Ferguson, C. McGrath, J. Deaven, D. E. Towell, R. G. Baker, L. Montoya, D. L. Duke, C. Hagmann, R. Kudo, N. Kornilov, E. Burgett, R. T. Thornton, M. P. Mendenhall, R. J. Casperson, and N. T. Pickle

Subjects
Nuclear physics, Normalization (statistics), Physics, Time projection chamber, 010308 nuclear & particles physics, Fission, Ionization, 0103 physical sciences, Neutron, MicroMegas detector, 010306 general physics, 01 natural sciences, Neutron temperature
Abstract

The normalized $^{238}$U(n,f)/$^{235}$U(n,f) cross section ratio has been measured using the NIFFTE fission Time Projection Chamber from the reaction threshold to $30$~MeV. The fissionTPC is a two-volume MICROMEGAS time projection chamber that allows for full three-dimensional reconstruction of fission-fragment ionization profiles from neutron-induced fission. The measurement was performed at the Los Alamos Neutron Science Center, where the neutron energy is determined from neutron time-of-flight. The $^{238}$U(n,f)/$^{235}$U(n,f) ratio reported here is the first cross section measurement made with the fissionTPC, and will provide new experimental data for evaluation of the $^{238}$U(n,f) cross section, an important standard used in neutron-flux measurements. Use of a development target in this work prevented the determination of an absolute normalization, to be addressed in future measurements. Instead, the measured cross section ratio has been normalized to ENDF/B-VIII.$\beta$5 at 14.5 MeV.

Published
2018

11. Particle decay of astrophysically-important 19Ne levels

Author

K. T. Schmitt, W. A. Peters, R. L. Kozub, P. Thompson, M. Matos, S. Ahn, D. W. Bardayan, A. Kontos, S. T. Pittman, U. Greife, Shuya Ota, K.L. Jones, K. A. Chipps, Steven Pain, M. S. Smith, L. Linhardt, A. Sachs, J. C. Blackmon, B. Manning, and P. D. O'Malley

Subjects
Nuclear physics, Physics, History, Particle decay, Computer Science Applications, Education
Abstract

The 15O(α,γ)19Ne reaction is an important trigger reaction leading to the rapid proton (rp) capture process in X-ray bursts. The primary uncertainty in determining its astrophysical rate is the uncertain α branching ratios of levels near Ex = 4.1 MeV in 19Ne. These states have been populated in a study of the 20Ne(p, d)19Ne reaction, and α branching ratios are reported in this manuscript.

Published
2019

12. 'Charge state studies of low energy heavy ions passing through hydrogen and helium gas'. Nucl.Instr.Meth. A(2003)198-214

Author

W. LIU, IMBRIANI, GIANLUCA, L. BUCHMANN, A. A. CHEN, J. M. DAURIA, A. DONOFRIO, S. ENGEL, L. GIALANELLA, U. GREIFE, D. HUNTER, A. HUSSEIN, D. A. HUTCHEON, A. OLIN, D. OTTEWELL, D. ROGALLA, J. ROGERS, G. ROY, AND F. TERRASI, ROMANO, MARIO, W., Liu, Imbriani, Gianluca, L., Buchmann, A. A., Chen, J. M., Dauria, A., Donofrio, S., Engel, L., Gialanella, U., Greife, D., Hunter, A., Hussein, D. A., Hutcheon, A., Olin, D., Ottewell, D., Rogalla, J., Roger, Romano, Mario, G., Roy, and AND F., Terrasi

Published
2003

14. Measuring radiative capture rates at DRAGON

Author

L. Buchmann, D.F. Ottewell, D. A. Hutcheon, Barry Davids, A. Rojas, Jennifer Fallis, U. Greife, Chris Ruiz, and U. Hager

Subjects
Nuclear physics, Radiative capture, Environmental science
Published
2013

15. Thed(7Li,p)8Li cross section nearE cm=0.61 MeV

Author

F. Strieder, L. Gialanella, U. Greife, C. Rolfs, S. Schmidt, W. H. Schulte, H. P. Trautvetter, D. Zahnow, F. Terrasi, L. Campajola, A. D’Onofrio, V. Roca, M. Romano, and M. Romoli

Subjects
Nuclear and High Energy Physics
Published
1996

16. Off-line production of a 7Be ion beam

Author

L. GIALANELLA, U. GREIFE, A. D'ONOFRIO, M. ROMANO, L. CAMPAJOLA, N. DE CESARE, G. GYURKY, IMBRIANI, GIANLUCA, A. ORDINE, C. ROLFS, D. ROGALLA, C. SABBARESE, E. SOMORJAI, F. STRIEDER, F. TERRASI, H. P. TRAUTVETTER, ROCA, VINCENZO, L., Gialanella, U., Greife, A., D'Onofrio, M., Romano, L., Campajola, N., DE CESARE, G., Gyurky, Imbriani, Gianluca, A., Ordine, Roca, Vincenzo, C., Rolf, D., Rogalla, C., Sabbarese, E., Somorjai, F., Strieder, F., Terrasi, and H. P., Trautvetter

Published
2002

17. 'Recoil separator ERNA*: improved measurements of the astrophysical key reaction 12C(alfa,gamma)16O.'

Author

D. ROGALLA, M. ALIOTTA, C. A. BARNES, L. CAMPAJOLA, A. DONOFRIO, L. GIALANELLA, U. GREIFE, IMBRIANI, GIANLUCA, A. ORDINE, ROCA, VINCENZO, C. ROLFS, C. SABBARESE, D. SCHURMANN, F. SCUMANN, F. STRIEDER, S. THEIS, F. TERRASI AND H. P. T.R.A.U.T.V.E.T.T.E.R., ROMANO, MARIO, D., Rogalla, M., Aliotta, C. A., Barne, L., Campajola, A., Donofrio, L., Gialanella, U., Greife, Imbriani, Gianluca, A., Ordine, Roca, Vincenzo, C., Rolf, Romano, Mario, C., Sabbarese, D., Schurmann, F., Scumann, F., Strieder, S., Thei, and F. TERRASI AND H. P. T. R. A. U. T. V. E. T. T. E., R.

Published
2001

18. Absolute cross section of 7Be(p,gamma)8B. Nucl. Phys. A 696 (2001) 219S

Author

F. STRIEDER, L. GIALANELLA, G. GYRKY, F. SCHMANN, R. BONETTI, C. BROGGINI, L. CAMPAJOLA, P. CORVISIERO, H. COSTANTINI, A. DONOFRIO, A. FORMICOLA, Z. FLP, G. GERVINO, U. GREIFE, A. GUGLIELMETTI, C. GUSTAVINO, IMBRIANI, GIANLUCA, M. JUNKER, P. G. P. MORONI, A. ORDINE, P. PRATI, ROCA, VINCENZO, D. ROGALLA, C. ROLFS, E. SOMORJAI, O. STRANIERO, F. TERRASI, H. P. TRAUTVETTER AND S. Z.A.V.A.T.A.R.E.L.L.I., ROMANO, MARIO, F., Strieder, L., Gialanella, G., Gyrky, F., Schmann, R., Bonetti, C., Broggini, L., Campajola, P., Corvisiero, H., Costantini, A., Donofrio, A., Formicola, Z., Flp, G., Gervino, U., Greife, A., Guglielmetti, C., Gustavino, Imbriani, Gianluca, M., Junker, P. G. P., Moroni, A., Ordine, P., Prati, Roca, Vincenzo, D., Rogalla, C., Rolf, Romano, Mario, E., Somorjai, O., Straniero, F., Terrasi, and H. P. TRAUTVETTER AND S. Z. A. V. A. T. A. R. E. L. L., I.

Published
2001

19. A new measuremets of the E1 amplitude in the 12C(alfa,gamma)16O reaction'

Author

L. GIALANELLA, M. ALIOTTA, U. GREIFE, D. ROGALLA, C. ROLFS, F. SCHUEMANN F. STRIEDER, S. THEIS, H. P. TRAUTVETTER, L. CAMPAJOLA, G. IMBRIANI V. ROCA, A. D'ONOFRIO, C. SABBARESE, F. TERRASI, C. AGODI, R. ALBA, A. DEL ZOPPO, P. FIGURA, P. SAPIENZA, C. SPITALERI, G. GYURKY, E. SOMORJAI, ROMANO, MARIO, L., Gialanella, M., Aliotta, U., Greife, D., Rogalla, C., Rolf, F. SCHUEMANN F., Strieder, S., Thei, H. P., Trautvetter, L., Campajola, G. IMBRIANI V., Roca, Romano, Mario, A., D'Onofrio, C., Sabbarese, F., Terrasi, C., Agodi, R., Alba, A., DEL ZOPPO, P., Figura, P., Sapienza, C., Spitaleri, G., Gyurky, and E., Somorjai

Published
2001

20. 'Direct measurement of the absolute cross section of of p( 7Be,gamma)8B'

Author

F. TERRASI, L. GIALANELLA, IMBRIANI, GIANLUCA, F. STRIEDER, L. CAMPAJOLA, A. D'ONOFRIO, U. GREIFE, G. GYURKY, C. LUBRITTO, A. ORDINE, ROCA, VINCENZO, C. ROLFS, D. ROGALLA, C. SABBARESE, E. SOMORJAI, H. P. TRAUTVETTER, ROMANO, MARIO, F., Terrasi, L., Gialanella, Imbriani, Gianluca, F., Strieder, L., Campajola, A., D'Onofrio, U., Greife, G., Gyurky, C., Lubritto, A., Ordine, Roca, Vincenzo, C., Rolf, Romano, Mario, D., Rogalla, C., Sabbarese, E., Somorjai, and H. P., Trautvetter

Published
2001

21. A new measurement of the E1 amplitude in 12C(α,γ)16O. Nuclear Physics A688(2001)254

Author

GIALANELLA, Lucio, M. ALIOTTA, D. ROGALLA, C. ROLFS, F. SCHUMANN, F. STRIEDER, S. THEIS, H. P. TRAUTVETTER, L. CAMPAJOLA, G. IMBRIANI, V. ROCA, M. ROMANO, D'ONOFRIO, Antonio, SABBARESE, Carlo, C. AGODI, R. ALBA, A. DEL ZOPPO, P. FIGUERA, P. SAPIENZA, C. SPITALERI, G. GYURKY, E. SOMORJAI, U. GREIFE, TERRASI, Filippo, Gialanella, Lucio, M., Aliotta, D., Rogalla, C., Rolf, F., Schumann, F., Strieder, S., Thei, H. P., Trautvetter, L., Campajola, G., Imbriani, V., Roca, M., Romano, D'Onofrio, Antonio, Sabbarese, Carlo, Terrasi, Filippo, C., Agodi, R., Alba, A., DEL ZOPPO, P., Figuera, P., Sapienza, C., Spitaleri, G., Gyurky, E., Somorjai, and U., Greife

Published
2001

22. 'Absolute cross section of 7Be(p,gamma)8B using a novel approach'

Author

L. GIALANELLA, F. STRIEDER, L. CAMPAJOLA, A. D'ONOFRIO, U. GREIFE, G. GYURKY, IMBRIANI, GIANLUCA, G. OLIVIERO, A. ORDINE, ROCA, VINCENZO, C. ROLFS, D. ROGALLA, C. SABBARESE, E. SOMORJAI, F. TERRASI, H. P. TRAUTVETTER, ROMANO, MARIO, L., Gialanella, F., Strieder, L., Campajola, A., D'Onofrio, U., Greife, G., Gyurky, Imbriani, Gianluca, G., Oliviero, A., Ordine, Roca, Vincenzo, C., Rolf, Romano, Mario, D., Rogalla, C., Sabbarese, E., Somorjai, F., Terrasi, and H. P., Trautvetter

Published
2000

23. Improving the [sup 33]S(p,γ)[sup 34]Cl Reaction Rate for Models of Classical Nova Explosions

Author

A. Parikh, Th. Faestermann, R. Krücken, V. Bildstein, S. Bishop, K. Eppinger, C. Herlitzius, O. Lepyoshkina, P. Maierbeck, D. Seiler, K. Wimmer, R. Hertenberger, H.-F. Wirth, J. Fallis, U. Hager, D. Hutcheon, Ch. Ruiz, L. Buchmann, D. Ottewell, B. Freeman, Ch. Wrede, A. García, B. Delbridge, A. Knecht, A. Sallaska, A. A. Chen, J. A. Clark, C. M. Deibel, B. Fulton, A. Laird, U. Greife, B. Guo, E. Li, Z. Li, G. Lian, Y. Wang, W. Liu, P. D. Parker, K. Setoodehnia, Paraskevi Demetriou, Rauno Julin, and Sotirios Harissopulos

Subjects
Physics, Nuclear reaction, Massless particle, Nucleosynthesis, Helium-3, Isotopes of chlorine, White dwarf, Astrophysics, Isotopes of helium, Abundance of the chemical elements
Abstract

Reduced uncertainty in the thermonuclear rate of the {sup 33}S(p,{gamma}){sup 34}Cl reaction would help to improve our understanding of nucleosynthesis in classical nova explosions. At present, models are generally in concordance with observations that nuclei up to roughly the calcium region may be produced in these explosive phenomena; better knowledge of this rate would help with the quantitative interpretation of nova observations over the S-Ca mass region, and contribute towards the firm establishment of a nucleosynthetic endpoint. As well, models find that the ejecta of nova explosions on massive oxygen-neon white dwarfs may contain as much as 150 times the solar abundance of {sup 33}S. This characteristic isotopic signature of a nova explosion could possibly be observed through the analysis of microscopic grains formed in the environment surrounding a nova and later embedded within primitive meteorites. An improved {sup 33}S(p,{gamma}){sup 34}Cl rate (the principal destruction mechanism for {sup 33}S in novae) would help to ensure a robust model prediction for the amount of {sup 33}S that may be produced. Finally, constraining this rate could confirm or rule out the decay of an isomeric state of {sup 34}Cl(E{sub x} = 146 keV, t{sub 1/2} = 32 m) as a source formore » observable gamma-rays from novae. We have performed several complementary experiments dedicated to improving our knowledge of the {sup 33}S(p,{gamma}){sup 34}Cl rate, using both indirect methods (measurement of the {sup 34}S({sup 3}He,t){sup 34}Cl and {sup 33}S({sup 3}He,d){sup 34}Cl reactions with the Munich Q3D spectrograph) and direct methods (in normal kinematics at CENPA, University of Washington, and in inverse kinematics with the DRAGON recoil mass separator at TRIUMF). Our results will be used with nova models to facilitate comparisons of model predictions with present and future nova observables.« less

Published
2011

24. Design of a New Recoil Separator for Measurements of Radiative Capture Reactions in Astrophysics

Author

Georg P. A. Berg, Jeff C. Blackmon, Manoel Couder, U. Greife, F. Montes, K. Ernst Rehm, Hendrik Schatz, Michael S. Smith, Michael Wiescher, Al Zeller, Isao Tanihara, Hooi Jin Ong, Atsushi Tamii, Tadafumi Kishimoto, Toshitaka Kajino, Shigeru Kubono, and Tatsushi Shima

Subjects
Nuclear reaction, Nuclear physics, Physics, Isotope, Conceptual design, Nucleosynthesis, Nuclear astrophysics, Radiative transfer, Physics::Accelerator Physics, Astrophysics, Nuclear Experiment, Recoil separator, Separator (electricity)
Abstract

The rates of proton‐ and alpha‐capture reactions on unstable proton‐rich nuclei are needed to understand the energy generation and element synthesis occurring in novae, X‐ray bursts, and other explosions. Direct measurements of the cross sections of some of these reactions are now possible with radioactive beams and a recoil separator. A new device for such measurements, the Separator for CApture Reactions [SECAR], is being designed for use at the Facility for Rare Isotope Beams (FRIB). The specifications and preliminary conceptual design will be discussed along with plans for the first set of measurements.

Published
2010

26. Single-neutron excitations in neutron-rich N = 51 nuclei

Author

J. S. Thomas, D. W. Bardayan, J. C. Blackmon, J. A. Cizewski, R. P. Fitzgerald, U. Greife, C. J. Gross, M. S. Johnson, K. L. Jones, R. L. Kozub, J. F. Liang, R. J. Livesay, Z. Ma, B. H. Moazen, C. D. Nesaraja, D. Shapira, M. S. Smith, and D. W. Visser

Published
2009

27. First Direct Measurement of the [sup 17]F(p,γ)[sup 18]Ne Cross Section

Author

K. A. Chipps, D. W. Bardayan, J. C. Blackmon, K. Y. Chae, U. Greife, R. Hatarik, R. L. Kozub, C. Matei, B. H. Moazen, C. D. Nesaraja, S. D. Pain, W. A. Peters, S. T. Pittman, J. F. Shriner, M. S. Smith, Jan Jolie, Andreas Zilges, Nigel Warr, and Andrey Blazhev

Subjects
Nuclear physics, Oxygen-17, Nuclear reaction, Physics, Isotope, Isotopes of neon, Nucleosynthesis, S-factor, Resonance, Atomic physics, Spectroscopy
Abstract

The rate of the 17F(p,γ)18Ne reaction is of significant importance in astrophysical events like novae and x‐ray bursts. A 3+ state in 18Ne predicted to dominate the rate was found at 599.8 keV using the 17F(p,p)17F reaction [1], but the resonance strength was unknown. For the first time, the 17F(p,γ)18Ne reaction has been measured directly with the Daresbury Recoil Separator, using a mixed beam of radioactive 17F and stable 17O from the HRIBF at ORNL. A γ width was found for the 599.8 keV resonance in 18Ne, and an upper limit on the direct capture S factor was determined at an intermediate energy of 800 keV.

Published
2009

28. Studies of nuclei close to [sup 132]Sn using single-neutron transfer reactions

Author

K. J. Jones, S. D. Pain, R. L. Kozub, A. S. Adekola, D. W. Bardayan, J. C. Blackmon, W. N. Catford, K. Y. Chae, K. Chipps, J. A. Cizewski, L. Erikson, A. L. Gaddis, U. Greife, R. Grzywacz, C. Harlin, R. Hatarik, J. A. Howard, J. James, R. Kapler, W. Królas, J. F. Liang, Z. Ma, C. Matei, B. H. Moazen, C. D. Nesaraja, P. D. O’Malley, N. P. Patterson, S. V. Paulauskas, D. Shapira, J. F. Shriner, M. Sikora, D. J. Sissom, M. S. Smith, T. P. Swan, J. S. Thomas, G. L. Wilson, K. Ernst Rehm, Birger B. Back, Henning Esbensen, and C.J. (Kim) Lister

Subjects
Nuclear physics, Deuterium, Chemistry, Nucleosynthesis, Q value, Nuclear structure, Neutron, Atomic physics, Nuclear Experiment, Ground state, Spectroscopy, Spectral line
Abstract

Neutron transfer reactions were performed in inverse kinematics using radioactive ion beams of 132Sn, 130Sn, and 134Te and deuterated polyethylene targets. Preliminary results are presented. The Q‐value spectra for 133Sn, 131Sn and 135Te reveal a number of previously unobserved peaks. The angular distributions are compatible with the expected lf7/2 nature of the ground state of 133Sn, and 2p3/2 for the 3.4 MeV state in 131Sn.

Published
2009

29. Experiments to Further the Understanding of the Triple-Alpha Process in Hot Astrophysical Scenarios

Author

N. R. Patel, U. Greife, K. E. Rehm, C. M. Deibel, J. Greene, D. Henderson, C. L. Jiang, B. P. Kay, H. Y. Lee, S. T. Marley, M. Notani, R. Pardo, X. D. Tang, K. Teh, K. Ernst Rehm, Birger B. Back, Henning Esbensen, and C.J. (Kim) Lister

Subjects
Nuclear physics, Physics, Nucleosynthesis, Excited state, Carbon-12, Alpha decay, Isotopes of boron, Particle detector, Triple-alpha process, Radioactive decay
Abstract

In astrophysics, the first excited 0+ state of 12C at 7.654 MeV (Hoyle state) is the most important in the triple‐α process for carbon nucleosynthesis. In explosive scenarios like supernovae, where temperatures of several 109 K are achieved, the interference of the Hoyle state with the second 0+ state located at 10.3 MeV in 12C becomes significant. The recent NACRE compilation of astrophysical reaction rates assumes a 2+ resonance at 9.1 MeV for which no experimental evidence exists. Thus, it is critical to explore in more detail the 7–10 MeV excitation energy region, especially the minimum between the two 0+ resonances for carbon nucleosynthesis. The states in 12C were populated through the β‐decay of 12B and 12N produced at the ATLAS (Argonne Tandem Linac Accelerator System) in‐flight facility. The decay of 12C into three alphas is detected in a Frisch grid twin ionization chamber, acting as a low‐threshold calorimeter. This minimizes the effects of β‐summing and allowed us to investigate the minimum ab...

Published
2009

30. First Direct Measurement of the 17F(p,gamma)18Ne Cross Section

Author

K A, Chipps, D W, Bardayan, J C, Blackmon, K Y, Chae, U, Greife, R, Hatarik, R L, Kozub, C, Matei, B H, Moazen, C D, Nesaraja, S D, Pain, W A, Peters, S T, Pittman, J F, Shriner, and M S, Smith

Abstract

The rate of the (17)F(p,gamma)(18)Ne reaction is important in various astrophysical events. A previous (17)F(p,p)(17)F measurement identified a 3;{+} state providing the strongest resonance contribution, but the resonance strength was unknown. We have directly measured the (17)F(p,gamma)(18)Ne reaction using a mixed beam of (17)F and (17)O at ORNL. The resonance strength for the 3;{+} resonance in (18)Ne was found to be omegagamma = 33 +/- 14(stat) +/-1 7(syst) meV, corresponding to a gamma width of Gamma_{gamma} = 56 +/- 24(stat) +/- 30(syst) meV. An upper limit on the direct capture of S(E)or= 65 keV b was determined at an energy of 800 keV.

Published
2008

31. Futher direct approaches to the nuclear reactions in the Sun

Author

U. GREIFE, C. ARPESELLA, E. BELLOTTI, K. BREND, C. BROGGINI, L. CAMPAJOLA, P. CORVISIERO, A. D'ONOFRIO, G. FIORENTINI, L. GIALANELLA, ROMANO, MARIO, U., Greife, C., Arpesella, E., Bellotti, K., Brend, C., Broggini, L., Campajola, P., Corvisiero, A., D'Onofrio, G., Fiorentini, L., Gialanella, and Romano, Mario

Published
1997

32. The d(7Li,p)8Li cross section near Ecm=0.61MeV

Author

F. STRIEDER, L. CAMPAJOLA, A. D'ONOFRIO, L. GIALANELLA, U. GREIFE, V. ROCA, C. ROLFS, ROMANO, MARIO, F., Strieder, L., Campajola, A., D'Onofrio, L., Gialanella, U., Greife, V., Roca, C., Rolf, and Romano, Mario

Published
1997

33. Nuclear Astrophysics studies by recoil mass separator

Author

L. GIALANELLA, K. B.R.A.N.D., L. CAMPAJOLA, A. D'ONOFRIO, U. GREIFE, E. HUTTEL, ROMANO, MARIO, L., Gialanella, K. B. R. A. N., D., Campajola, . L., A., D'Onofrio, U., Greife, E., Huttel, and Romano, Mario

Published
1997

34. Production of an 8.0MeV 7Be ion beam at the Naples TTT-3 accelerator

Author

L. Campajola, L. Gialanella, K. Brand, A. D'Onofrio, U. Greife, E. Huttel, R. Kubat, G. Oliviero, H. Rebel, C. Rolfs, M. M. Romoli, S. Schmidt, W. H. Schulte, F. Strieder, F. Terrasi, H. P. Trautvetter, D. Zahnow, ROCA, VINCENZO, ROMANO, MARIO, L., Campajola, L., Gialanella, K., Brand, A., D'Onofrio, U., Greife, E., Huttel, R., Kubat, G., Oliviero, H., Rebel, Roca, Vincenzo, C., Rolf, Romano, Mario, M. M., Romoli, S., Schmidt, W. H., Schulte, F., Strieder, F., Terrasi, H. P., Trautvetter, and D., Zahnow

Subjects
astrofisica nucleare, 7Be
Published
1996

35. Measurement of the Ec.m. = 184 keV resonance strength in the 26gAl (p, gamma)27 Si reaction

Author

C, Ruiz, A, Parikh, J, José, L, Buchmann, J A, Caggiano, A A, Chen, J A, Clark, H, Crawford, B, Davids, J M, D'Auria, C, Davis, C, Deibel, L, Erikson, L, Fogarty, D, Frekers, U, Greife, A, Hussein, D A, Hutcheon, M, Huyse, C, Jewett, A M, Laird, R, Lewis, P, Mumby-Croft, A, Olin, D F, Ottewell, C V, Ouellet, P, Parker, J, Pearson, G, Ruprecht, M, Trinczek, C, Vockenhuber, and C, Wrede

Abstract

The strength of the Ec.m. = 184 keV resonance in the 26gAl(p, gamma)27 reaction has been measured in inverse kinematics using the DRAGON recoil separator at TRIUMF's ISAC facility. We measure a value of omega gamma = 35 +/- 7 microeV and a resonance energy of Ec.m. = 184 +/- 1 keV, consistent with p-wave proton capture into the 7652(3) keV state in 27Si, and discuss the implications of these values for 26GAl nucleosynthesis in typical oxygen-neon white-dwarf novae.

Published
2006

36. Nuclear Reactions Rates

Author

C. Rolfs and U. Greife

Subjects
Nuclear reaction, Radiochemistry
Published
2004

37. 21Na(p,gamma)22Mg reaction and oxygen-neon novae

Author

S, Bishop, R E, Azuma, L, Buchmann, A A, Chen, M L, Chatterjee, J M, D'Auria, S, Engel, D, Gigliotti, U, Greife, M, Hernanz, D, Hunter, A, Hussein, D, Hutcheon, C, Jewett, J, José, J, King, S, Kubono, A M, Laird, M, Lamey, R, Lewis, W, Liu, S, Michimasa, A, Olin, D, Ottewell, P D, Parker, J G, Rogers, F, Strieder, and C, Wrede

Abstract

The 21Na(p,gamma)22Mg reaction is expected to play an important role in the nucleosynthesis of 22Na in oxygen-neon novae. The decay of 22Na leads to the emission of a characteristic 1.275 MeV gamma-ray line. This report provides the first direct measurement of the rate of this reaction using a radioactive 21Na beam, and discusses its astrophysical implications. The energy of the important state was measured to be E(c.m.)=205.7+/-0.5 keV with a resonance strength omegagamma=1.03+/-0.16(stat)+/-0.14(sys) meV.

Published
2002

38. The Single-Particle Structure of Neutron-Rich Nuclei of Astrophysical Interest at the Ornl Hribf

Author

D.W. BARDAYAN, J.C. BATCHELDER, J.C. BLACKMON, C.R. BRUNE, A.E. CHAMPAGNE, J.A. CIZEWSKI, T. DAVINSON, U. GREIFE, A.N. JAMES, M. JOHNSON, R.L. KOZUB, J.F. LIANG, R.J. LIVESAY, Z. MA, C.D. NESARAJA, D.C. RADFORD, D. SHAPIRA, M.S. SMITH, J. S. THOMAS, P.J. WOODS, E. ZGANJAR, and null UNIRIB COLLABORATION

Subjects
Baton rouge, Nuclear Theory, FOS: Physical sciences, Physics::Accelerator Physics, Oak Ridge National Laboratory, Nuclear Experiment (nucl-ex), Nuclear Experiment, Archaeology
Abstract

The rapid nuetron-capture process (r process) produces roughly half of the elements heavier than iron. The path and abundances produced are uncertain, however, because of the lack of nuclear strucure information on important neutron-rich nuclei. We are studying nuclei on or near the r-process path via single-nucleon transfer reactions on neutron-rich radioactive beams at ORNL's Holifield Radioactive Ion Beam Facility (HRIBF). Owing to the difficulties in studying these reactions in inverse kinematics, a variety of experimental approaches are being developed. We present the experimental methods and initial results., Proceedings of the Third International Conference on Fission and Properties of Neutron-Rich Nuclei

Published
2002

40. Electron screening and ion stopping power at low energy

Author

H. COSTANTINI, A. FORMICOLA, M. JUNKER, R. BONETTI, C. BROGGINI, L. CAMPAJOLA, P. CORVISIERO, A. FUBINI, G. GERVINO, L. GIALANELLA, U. GREIFE, A. GUGLIELMETTI, C. GUSTAVINO, G. IMBRIANI, P. G. P. MORONI, A. ORDINE, P. PRATI, V. ROCA, C. ROLFS, M. ROMANO, F. SCHÜMANN, O. STRANIERO, F. STRIEDER, TERRASI, Filippo, H. P. TRAUTVETTER, S. ZAVATARELLI, D'ONOFRIO, Antonio, Costantini, H., Formicola, A., Junker, M., Bonetti, R., Broggini, C., Campajola, L., Corvisiero, P., D'Onofrio, Antonio, Fubini, A., Gervino, G., Gialanella, L., Greife, U., Guglielmetti, A., Gustavino, C., Imbriani, G., Moroni, P. G. P., Ordine, A., Prati, P., Roca, V., Rolfs, C., Romano, M., Schümann, F., Straniero, O., Strieder, F., Terrasi, Filippo, Trautvetter, H. P., and Zavatarelli, S.

Published
2000

41. Experimental approach to a direct study of the nuclear reaction H([sup 7]Be,γ)[sup 8]B

Author

S. Schmidt, Filippo Terrasi, Lucio Gialanella, G. Oliviero, W. H. Schulte, R. Kubat, L. Campajola, K. Brand, V. Roca, E. Huttel, D. Zahnow, U. Greife, A. D'Onofrio, H. Rebel, C. Rolfs, M. Romoli, F. Strieder, Mario R. Romano, and H. P. Trautvetter

Subjects
Nuclear physics, Nuclear reaction, Physics, Stars, Recoil, medicine.anatomical_structure, Nucleosynthesis, medicine, Nuclear fusion, Cosmic ray, Neutrino, Nuclear Experiment, Nucleus
Abstract

Nuclear fusion reactions play a key role in the understanding of energy production, neutrino emission and nucleosynthesis of the elements in stars. The direct measurement of the cross section of these reactions at the relevant energies is usually hampered by cosmic radiation, beam induced background and/or the radioactivity of the nuclei involved. In order to suppress these background contributions one can either place an experiment underground [1,2] or exploit coincedence techniques between the reaction products. The major aspect in this contribution is the efficient detection of the recoil nucleus in a direct capture reaction.

Published
1997

42. The d(7Li,p)8Li Cross Section near Ecm=0.61 MeV

Author

F. STRIEDER, L. CAMPAJOLA, L. GIALANELLA, U. GREIFE, V. ROCA, C. ROLFS, M. ROMANO, M. ROMOLI, S. SCHMIDT, W. H. SCHULTE, H. P. TRAUTVETTER, D. ZAHNOW, D'ONOFRIO, Antonio, Strieder, F., Campajola, L., D'Onofrio, Antonio, Gialanella, L., Greife, U., Roca, V., Rolfs, C., Romano, M., Romoli, M., Schmidt, S., Schulte, W. H., Trautvetter, H. P., and Zahnow, D.

Published
1997

43. A recoil separator for the measurement of radiative capture reactions. Nuclear Instruments and Methods in Physics Research A376(1996)174

Author

L. GIALANELLA, F. STRIEDER, K. BRAND, L. CAMPAJOLA, D'ONOFRIO, Antonio, U. GREIFE, E. HUTTEL, F. PETRAZZUOLO, V. ROCA, C. ROLFS, M. ROMANO, M. ROMOLI, S. SCHMIDT, W. H. SCHULTE, H. P. TRAUTVETTER, D. ZAHNOW, TERRASI, Filippo, Gialanella, L., Strieder, F., Brand, K., Campajola, L., D'Onofrio, Antonio, Greife, U., Huttel, E., Petrazzuolo, F., Roca, V., Rolfs, C., Romano, M., Romoli, M., Schmidt, S., Schulte, W. H., Terrasi, Filippo, Trautvetter, H. P., and Zahnow, D.

Published
1996

44. Production of an 8.0 MeV 7Be beam at the Naples TTT-3 accelerator. Zeitschrift fur Physik A356(1996)107

Author

L. CAMPAJOLA, L. GIALANELLA, K, BRAND, D'ONOFRIO, Antonio, U. GREIFE, E. HUTTEL, R. KUBAT, G. OLIVIERO, H. REBEL, V. ROCA, C. ROLFS, M. ROMANO, M. ROMOLI, S. SCHMIDT, W. H. SCHULTE, F. STRIEDER, H. P. TRAUTVETTER, D. ZAHNOW, TERRASI, Filippo, Campajola, L., Gialanella, L., Brand, K, D'Onofrio, Antonio, Greife, U., Huttel, E., Kubat, R., Oliviero, G., Rebel, H., Roca, V., Rolfs, C., Romano, M., Romoli, M., Schmidt, S., Schulte, W. H., Strieder, F., Terrasi, Filippo, Trautvetter, H. P., and Zahnow, D.

Published
1996

46. Absolute cross section of 7Be(p,γ)8B

Author

Uwe Greife, Zs. Fülöp, F. Schümann, L. Campajola, Antonio D'Onofrio, Gianluca Imbriani, C. Rolfs, Lucio Gialanella, Vincenzo Roca, P. Corvisiero, Paolo Prati, Frank Strieder, Sandra Zavatarelli, G. Gervino, Oscar Straniero, H. Costantini, A. Ordine, Filippo Terrasi, A. Formicola, E. Somorjai, Carlo Broggini, C. Gustavino, P. G. Prada Moroni, A. Guglielmetti, R. Bonetti, Gy. Gyürky, H. P. Trautvetter, M. Junker, Mario R. Romano, Detlef Rogalla, F., Strieder, L., Gialanella, G., Gyürky, F., Schümann, R., Bonetti, C., Broggini, L., Campajola, P., Corvisiero, H., Costantini, A., D'Onofrio, A., Formicola, Z., Fülöp, G., Gervino, U., Greife, A., Guglielmetti, C., Gustavino, Imbriani, Gianluca, M., Junker, P. G. P., Moroni, A., Ordine, P., Prati, Roca, Vincenzo, D., Rogalla, C., Rolf, Romano, Mario, E., Somorjai, O., Straniero, F., Terrasi, H. P., Trautvetter, and S., Zavatarelli

Subjects
Experimental Nuclear Physic, Physics, Nuclear reaction, Nuclear and High Energy Physics, Cross section (physics), Radiative capture, Zero-point energy, Nuclide, Atomic physics, Experimental Nuclear Astrophysic, Solar neutrino, Stellar hydrogen burning
Abstract

The absolute cross section σ ( E ) for the radiative capture reaction 7 Be(p, γ ) 8 B at the center-of-mass energies E =0.32 to 2.61 MeV has been measured using a 7 Be target deposited on a Cu backing and observing the β -delayed α -particles from 8 B. The backing causes a loss of less than 1% of the 8 B residual nuclides. The resulting astrophysical S ( E ) factor at zero energy, S (0)=18.4±1.6 eV b, is consistent only with a restricted data set from previous work.

Published
2001

47. The E1 capture amplitude in 12C(α,γ0) 16O

Author

F. Strieder, Antonio D'Onofrio, A. Ordine, Marialuisa Aliotta, Filippo Terrasi, C. Agodi, Detlef Rogalla, G. Gyürki, L. Gialanella, E. Somorjai, Vincenzo Roca, L. Campajola, Gianluca Imbriani, P. Figuera, Mario R. Romano, H. P. Trautvetter, S. Theis, Uwe Greife, A. Del Zoppo, C. Rolfs, R. Alba, F. Schümann, Paolo Sapienza, Carlo Sabbarese, Gialanella, L., Rogalla, D., Strieder, F., Theis, S., Gyurki, G., Agodi, C., Alba, R., Aliotta, M., Campajola, L., Del Zoppo, A., D'Onofrio, A., Figuera, P., Greife, U., Imbriani, G., Ordine, A., Roca, V., Rolfs, C., Romano, M., Sabbarese, C., Sapienza, P., Schumann, F., Somorjai, E., Terrasi, F., Trautvetter, H. P., L., Gialanella, D., Rogalla, F., Strieder, S., Thei, G., Gyürki, C., Agodi, R., Alba, M., Aliotta, L., Campajola, A., Del Zoppo, A., D'Onofrio, P., Figuera, U., Greife, Imbriani, Gianluca, A., Ordine, Roca, Vincenzo, C., Rolf, Romano, Mario, C., Sabbarese, P., Sapienza, F., Schümann, E., Somorjai, F., Terrasi, and H. P., Trautvetter

Subjects
Physics, Excitation function, Nuclear and High Energy Physics, S-factor, Monte Carlo method, Detector, Hadron, Extrapolation, Nuclear physics, Helium burining, Amplitude, Nuclear fusion, Experimental nuclear physic, Nuclear Astrophysic
Abstract

An excitation function of the ground-state gamma (0)-ray capture transition in C-12(alpha, gamma)O-16 at theta (gamma) = 90 degrees was obtained in far geometry using six Ge detectors, where the study of the reaction was initiated in inverse kinematics involving a windowless gas target. The detectors observed predominantly the El capture amplitude. The data at E = 1.32 to 2.99 MeV lead to an extrapolated astrophysical S factor S-E1(E-0) = 90 +/- 15 keV b at E-0 = 0.3 MeV (for the case of constructive interference between the two lowest E1 sources), in good agreement with previous works. However, a novel Monte Carlo approach in the data extrapolation reveals systematic differences between the various data sets such that a combined analysis of all available data sets could produce a biased estimate of the S-E1(E-0) value. As a consequence, the case of destructive interference between the two lowest E1 sources with S-E1(E-0) = 8 +/- 3 keV b cannot be ruled out rigorously.

Published
2001

48. A new measurement of the E1 amplitude in 12C(α,γ0)16O

Author

L. Gialanella, Antonio D'Onofrio, E. Somorjai, Paolo Sapienza, Detlef Rogalla, C. Spitaleri, Vincenzo Roca, Frank Strieder, S. Theis, Gianluca Imbriani, L. Campajola, H. P. Trautvetter, Gyuri Gyürky, Mario R. Romano, Uwe Greife, Marialuisa Aliotta, Filippo Terrasi, C. Agodi, F. Schümann, Carlo Sabbarese, C. Rolfs, R. Alba, P. Figuera, A. Del Zoppo, L., Gialanella, M., Aliotta, D., Rogalla, C., Rolf, F., Schümann, F., Strieder, S., Thei, H. P., Trautvetter, L., Campajola, Imbriani, Gianluca, Roca, Vincenzo, Romano, Mario, A., D'Onofrio, C., Sabbarese, F., Terrasi, C., Agodi, R., Alba, A., Del Zoppo, P., Figuera, P., Sapienza, C., Spitaleri, G., Gyurky, E., Somorjai, and U., Greife

Subjects
Experimental Nuclear Physic, Physics, Nuclear and High Energy Physics, Amplitude, Quantum electrodynamics, Helium burning in Stars, Nuclear Astrophysic
Abstract

The El amplitude of the transition to the ground state in the C-12(alpha, gamma)O-16 capture reaction was measured in the energy range E-cm=1.3 to 3.0 MeV using an intense C-12 beam in combination with a windowless He-4 gas target and an array of six 70% HPGe detectors. The detectors were placed in a ring-shaped geometry around the target at a distance of 17 cm on a plane perpendicular to the beam axis. A target length of 5.3 cm was defined by a 12.5 cm thick lead shielding. Passive and active shielding was used to achieve the necessary suppression of the beam induced and cosmic background. The results of this measurement and their extrapolation to the relevant energy during the helium burning phase in massive stars are reported.

Published
2001

49. Recoil separator ERNA: ion beam specifications

Author

C. Rolfs, Gianluca Imbriani, L. Gialanella, C. A. Barnes, A. Ordine, Vincenzo Roca, D. Schürmann, E. Fritz, Antonio D'Onofrio, L. Campajola, Mario R. Romano, F. Schümann, Carlo Sabbarese, Uwe Greife, H. P. Trautvetter, Detlef Rogalla, J. Ossmann, Frank Strieder, S. Theis, Marialuisa Aliotta, Filippo Terrasi, D., Rogalla, M., Aliotta, C. A., Barne, L., Campajola, A., D'Onofrio, E., Fritz, L., Gialanella, U., Greife, Imbriani, Gianluca, A., Ordine, J., Ossmann, Roca, Vincenzo, C., Rolf, Romano, Mario, C., Sabbarese, D., Schurmann, F., Schumann, F., Strieder, S., Thei, F., Terrasi, H. P., Trautvetter, D., Schürmann, and F., Schümann

Subjects
Experimental Nuclear Physic, Physics, Nuclear physics, Momentum, Nuclear and High Energy Physics, Wien filter, Ion beam, Dipole magnet, Magnet, Nuclear Astrophysics, Separator (oil production), Dynamitron, Beam (structure)
Abstract

For improved measurements of the key astrophysical reaction C-12(alpha, gamma)O-16 in inverted kinematics, a recoil separator ERNA is being developed at the 4 MV Dynamitron tandem accelerator in Bochum to detect directly the O-16 recoils with about 50% efficiency. Calculations of the ion beam optics including all filtering and focusing elements of ERNA are presented. Since the C-12 projectiles and the O-16 recoils have essentially the same momentum, and since the C-12 ion beam emerging from the accelerator passes through a momentum filter (analysing magnet), the C-12 ion beam must be as free as possible from O-16 contamination for ERNA to succeed. In the present work, the O-16 contamination was reduced from a level of 1 x 10(-11) to a level below 2 x 10(-29) by the installation of Wien filters both before and after the analysing magnet. The measurement of these and other beam specifications involved other parts of the final ERNA layout - sequentially a Wien filter, a 60 degrees dipole magnet, another Wien filter, and a Delta E-E telescope. The setup led to a measured suppression factor of 5 x 10(-18) for the C-12 ion beam. The experiments also indicate that an almost free choice of the charge state for the O-16 recoils is possible in the separator.

Published
1999

50. Recoil separator ERNA: improved measurements of the astrophysical key reaction 12C(α,γ)16O

Author

Gianluca Imbriani, H. P. Trautvetter, L. Campajola, Lucio Gialanella, Vincenzo Roca, C. Rolfs, Frank Strieder, Uwe Greife, Mario R. Romano, Detlef Rogalla, Marialuisa Aliotta, Filippo Terrasi, A. Ordine, S. Theis, C. A. Barnes, Antonio D'Onofrio, F. Schümann, Carlo Sabbarese, D. Schürmann, D., Rogalla, M., Aliotta, C. A., Barne, L., Campajola, A., D'Onofrio, L., Gialanella, U., Greife, Imbriani, Gianluca, A., Ordine, Roca, Vincenzo, C., Rolf, Romano, Mario, C., Sabbarese, D., Schürmann, F., Schümann, F., Strieder, S., Thei, F., Terrasi, and H. P., Trautvetter

Subjects
Experimental Nuclear Physic, Physics, Nuclear physics, Nuclear and High Energy Physics, Range (particle radiation), Nuclear Astrophysics, Nuclear astrophysics, Atomic physics, Tandem accelerator, Nuclear Experiment, Dynamitron, Recoil separator
Abstract

The recoil separator ERNA (European Recoil Separator for Nuclear Astrophysics) for improved measurements of the astrophysical key reaction C-12(alpha, gamma)O-16 is being developed at the 4 MV Dynamitron tandem accelerator in Bochum to detect directly the O-16 recoils. The total detection efficiency of about 50 % allows direct measurements in a much wider energy range than previously accessible. In addition this technique allows improved measurements not hampered by cosmic background problems when compared to gamma -ray detection.

Published
2001

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