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Your search keyword '"A. J. Chewter"' showing total 14 results
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14 results on '"A. J. Chewter"'

1. Recoil-fission tagging of the transfermium nucleus 252No

Author

W. Korten, C. Scholey, C. J. Lister, R. D. Page, P. Reiter, O. Stezowski, Ch. Schlegel, R. Lucas, M. Nyman, J. F. C. Cocks, F. P. Heßberger, G. D. Jones, Paul Greenlees, H. J. Wollersheim, K. J. Eskola, Wladyslaw Henryk Trzaska, J. Gerl, K. Helariutta, Matti Leino, Y. Le Coz, S. Juutinen, F. Becker, Jan Sarén, H. Kankaanpää, Peter M. Jones, M. Muikku, P. Rahkila, N. Amzal, O. Dorvaux, Janne Pakarinen, M. Houry, Paivi Nieminen, S. Eeckhaudt, Ch. Theisen, T. L. Khoo, T. Grahn, R.-D. Herzberg, Juha Uusitalo, Pasi Kuusiniemi, A.-P. Leppänen, R. Julin, N. J. Hammond, Heikki Kettunen, P. A. Butler, K. Hauschild, and A. J. Chewter

Subjects
Physics, Nuclear and High Energy Physics, Fission, Nuclear Theory, Gamma ray, Computer Science::Computation and Language (Computational Linguistics and Natural Language and Speech Processing), Spectral line, Nuclear physics, Recoil, medicine.anatomical_structure, medicine, Nuclear fusion, High Energy Physics::Experiment, Alpha decay, Atomic physics, Nuclear Experiment, Nucleus, Spontaneous fission
Abstract

An in-beam study of the transfermium nucleus 252No has been performed using the JUROSPHERE II array of germanium detectors coupled to the gas-filled recoil separator RITU. A new technique of recoil-fission tagging was used to extract tagged γ-ray data. Having significant spontaneous fission and α-decay branches, 252No is an ideal candidate for a comparative study. In a similar manner to α-decay tagging the fission events can be used to obtain γ-ray data. The recoil-fission tagged γ-ray spectrum showed a similar structure to the α-decay tagged γ-ray spectrum. By comparing the α-tagged and fission-tagged spectra and decay curves, it was shown that the spontaneous fission originates from the same initial state as the α decay. This extension of the tagging method allows in-beam spectroscopic data to be obtained from heavy nuclei with significant spontaneous-fission branches.

Published
2006

2. In-beam spectroscopy of 253, 254No

Author

R. D. Humphreys, K. Eskola, Panu Rahkila, Juha Uusitalo, Ch. Schlegel, O. Stezowski, F. P. Heßberger, A. J. Chewter, H. Kankaanpää, T. L. Khoo, Ch. Theisen, G. Sletten, J. Gerl, S. Juutinen, T. Page, K. Hauschild, M. Muikku, Heikki Kettunen, O. Dorvaux, Paul Greenlees, M. Houry, P. A. Butler, F. Becker, Paivi Nieminen, Pasi Kuusiniemi, R. D. Page, P. M. T. Brew, C. Scholey, Wladyslaw Henryk Trzaska, N. Amzal, J. F. C. Cocks, R. Lucas, P. Reiter, R. Julin, N. J. Hammond, K. Helariutta, Matti Leino, A.P. Leppänen C.J. Lister, G. D. Jones, Peter M. Jones, H. J. Wollersheim, Y. Le Coz, J. E. Bastin, A. Hürstel, R.-D. Herzberg, and W. Korten

Subjects
Physics, Nuclear and High Energy Physics, Electron spectrometer, Monte Carlo method, Nuclear fusion, Atomic physics, Nuclear Experiment, Spectroscopy, Electron spectroscopy, Beam (structure), Spectral line, Separator (electricity)
Abstract

In-beam conversion electron spectroscopy experiments have been performed on the transfermium nuclei 253, 254No using the conversion electron spectrometer SACRED in nearly collinear geometry in conjunction with the gas-filled separator RITU at the University of Jyvaskyla. The experimental setup is discussed and the spectra are compared to Monte Carlo simulations. The implications for the ground-state configuration of 253No are discussed.

Published
2002

3. Entry Distribution, Fission Barrier, and Formation Mechanism ofN102254o

Author

P. Reiter, T. L. Khoo, T. Lauritsen, C. J. Lister, D. Seweryniak, A. A. Sonzogni, I. Ahmad, N. Amzal, P. Bhattacharyya, P. A. Butler, M. P. Carpenter, A. J. Chewter, J. A. Cizewski, C. N. Davids, K. Y. Ding, N. Fotiades, J. P. Greene, P. T. Greenlees, A. Heinz, W. F. Henning, R.-D. Herzberg, R. V. F. Janssens, G. D. Jones, F. G. Kondev, W. Korten, M. Leino, S. Siem, J. Uusitalo, K. Vetter, and I. Wiedenhöver

Subjects
Physics, Angular momentum, Fission, Yrast, Nuclear Theory, Dirac (software), General Physics and Astronomy, Neutron, Atomic physics, Nuclear Experiment, Spin (physics), Energy (signal processing), Excitation
Abstract

The entry distribution in angular momentum and excitation energy for the formation of {sup 254}No has been measured after the {sup 208}Pb( {sup 48}Ca, 2 n) reaction at 215 and 219 MeV. This nucleus is populated up to spin 22({Dirac_h}/2{pi}) and excitation energy (greater-or-similar sign)6 MeV above the yrast line, with the half-maximum points of the energy distributions at {approx}5 MeV for spins between 12({Dirac_h}/2{pi}) and 22({Dirac_h}/2{pi}) . This suggests that the fission barrier is (greater-or-similar sign)5 MeV and that the shell-correction energy persists to high spin. (c) 2000 The American Physical Society.

Published
2000

4. In-beam study of 254No

Author

J. Gerl, W. Korten, Ch. Schlegel, Pasi Kuusiniemi, H.J. Wollersheim, P. Reiter, K. Eskola, Y. Le Coz, A. Kleinböhl, H. Kankaanpää, A. J. Chewter, R. Julin, F. Becker, A. Savelius, O. Dorvaux, Wladyslaw Henryk Trzaska, K. Helariutta, S. Juutinen, Heikki Kettunen, Panu Rahkila, M. Muikku, P.M. Jones, P. A. Butler, R. D. Page, R. Lucas, F. P. Heßberger, R-D Herzberg, M. Houry, Paul Greenlees, Paivi Nieminen, Matti Leino, J. F. C. Cocks, G. D. Jones, T. L. Khoo, and Ch. Theisen

Subjects
Physics, Nuclear and High Energy Physics, 010308 nuclear & particles physics, Hadron, 7. Clean energy, 01 natural sciences, Recoil, Excited state, 0103 physical sciences, Quadrupole, Nuclide, Atomic physics, 010306 general physics, Ground state, Spectroscopy, Excitation
Abstract

Excited states of the Z = 102 nuclide 254No have been studied in the reaction 208Pb(48Ca,2n) by means of in-beam γ -ray spectroscopy in combination with recoil gating and recoil decay tagging. A Ge detector array, consisting of four clover detectors, and a gas-filled separator were used. Six γ-ray lines were observed and associated with E2 transitions in the ground state band of 254No, the highest-lying of these being the 16+→ 14+ transition. Based on global systematics and the extrapolated 2+ 1 excitation energy, the value β2= 0.27 ± 0.03 was extracted for the quadrupole deformation. An improved value for the half-life of 254No, T1/2= (48 ± 3) s, was determined.

Published
1999

5. Ground-State Band and Deformation of theZ=102IsotopeN254o

Author

W. Korten, W. F. Henning, P. Reiter, Paul Greenlees, M. Leino, A. J. Chewter, J. D. Fox, M. P. Carpenter, Iftikhar Ahmad, D. Seweryniak, R. V. F. Janssens, D. Sullivan, I. Wiedenhöver, John P. Greene, C. N. Davids, T. L. Khoo, R.-D. Herzberg, Kai Vetter, P. A. Butler, Jolie Cizewski, N. Amzal, G. D. Jones, M. Alcorta, Sunniva Siem, C. J. Lister, Juha Uusitalo, T. Lauritsen, G. Gervais, K. Y. Ding, N. Fotiades, and A. A. Sonzogni

Subjects
Physics, Isotope, Fission, Band gap, Nuclear Theory, Quadrupole, General Physics and Astronomy, Atomic physics, Deformation (meteorology), Ground state, Energy (signal processing), Spin-½
Abstract

The ground-state band of the Z=102 isotope {sup 254}No has been identified up to spin 14, indicating that the nucleus is deformed. The deduced quadrupole deformation, {beta}=0.27 , is in agreement with theoretical predictions. These observations confirm that the shell-correction energy responsible for the stability of transfermium nuclei is partly derived from deformation. The survival of {sup 254}No up to spin 14 means that its fission barrier persists at least up to that spin. {copyright} {ital 1999} {ital The American Physical Society }

Published
1999

6. High-Spin Structures of the Odd-A 97 - 105 43 Tc Isotopes

Author

Stephane Perries, T. Kröll, A. J. Chewter, A. Astier, Josette Duprat, S. Courtin, Ts. Venkova, R. Cunningham, A. Nowak, N. Redon, N. Buforn, R-D Herzberg, N. Schulz, M. Houry, Marco Meyer, E. Piasecki, W. Urban, C. M. Petrache, B. J. P. Gall, P. A. Butler, G. Duchêne, R. Lucas, F. Hoellinger, I. Deloncle, A. Bauchet, N. Amzal, and M. G. Porquet

Subjects
Physics, Nuclear and High Energy Physics, Isotope, Proton, Fission, Yrast, Nuclear Theory, Hadron, General Physics and Astronomy, Nuclear physics, Neutron number, Nuclear fusion, Atomic physics, Nuclear Experiment, Spin-½
Abstract

The 99−105Tc isotopes have been produced at high spin as fission fragments following the fusion reaction 37Cl(170 MeV) + 176Yb and studied with the Euroball3 array. The high-spin structures of 103Tc have been identified for the first time. From the systematics of the yrast states of 97−105Tc, the location of individual proton states can be analyzed as a function of the neutron number.

Published
2001

7. Structure of the Odd-A, Shell-Stabilized NucleusNo102253

Author

A. J. Chewter, C. N. Davids, R.-D. Herzberg, F. G. Kondev, John P. Greene, I. Wiedenhöver, P. Reiter, K. Helariutta, T. L. Khoo, Pasi Kuusiniemi, D. Seweryniak, C. J. Lister, H. Kankaanpää, J. Uusitalo, T. Lauritsen, M. P. Carpenter, Jolie Cizewski, S. Siem, Matti Leino, R. V. F. Janssens, R. Julin, P. Bhattacharyya, A. M. Heinz, G. D. Jones, A. V. Afanasjev, Heikki Kettunen, P. A. Butler, I. Ahmad, Paul Greenlees, and A. A. Sonzogni

Subjects
Physics, Matrix (mathematics), Dirac (software), Shell (structure), General Physics and Astronomy, Gamma spectroscopy, Atomic physics, Moment of inertia, Spin (physics), Energy (signal processing), Spectral line
Abstract

In-beam {gamma}-ray spectroscopic measurements have been made on {sub 102}{sup 253}No. A single rotational band was identified up to a probable spin of 39/2({Dirac_h}/2{pi}), which is assigned to the 7/2{sup +}[624] Nilsson configuration. The bandhead energy and the moment of inertia provide discriminating tests of contemporary models of the heaviest nuclei. Novel methods were required to interpret the sparse data set associated with cross sections of around 50 nb. These methods included comparisons of experimental and simulated spectra, as well as testing for evidence of a rotational band in the {gamma}{gamma} matrix.

Published
2005

8. In-beam spectroscopy of $^{253,254}$No

Author

W. H. Trzaska, W. Korten, R. D. Humphreys, C. J. Lister, P. M. T. Brew, G. Sletten, S. Juutinen, N. J. Hammond, P. Rahkila, A. Hürstel, H. J. Wollersheim, M. Muikku, Matti Leino, R.-D. Herzberg, P. Reiter, Y. Le Coz, T. L. Khoo, Juha Uusitalo, J. E. Bastin, T. Page, N. Amzal, Pasi Kuusiniemi, Ch. Theisen, M. Houry, J. F. C. Cocks, R. Julin, Paul Greenlees, Ch. Schlegel, O. Dorvaux, A. J. Chewter, O. Stezowski, F. P. Heßberger, A. P. Leppänen, C. Scholey, J. Gerl, K. Hauschild, G. D. Jones, Peter M. Jones, R. D. Page, R. Lucas, Paivi Nieminen, F. Becker, K. J. Eskola, K. Helariutta, H. Kankaanpää, Heikki Kettunen, P. A. Butler, Institut de Recherches Subatomiques (IReS), Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Cancéropôle du Grand Est-Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique (CNRS), Institut de Physique Nucléaire de Lyon (IPNL), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)-Centre National de la Recherche Scientifique (CNRS), Heyd, Yvette, Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), and Université de Lyon-Université de Lyon-Institut National de Physique Nucléaire et de Physique des Particules du CNRS (IN2P3)

Subjects
Physics, Electron spectrometer, 010308 nuclear & particles physics, [PHYS.NEXP] Physics [physics]/Nuclear Experiment [nucl-ex], Monte Carlo method, Separator (oil production), [PHYS.NEXP]Physics [physics]/Nuclear Experiment [nucl-ex], 7. Clean energy, 01 natural sciences, Electron spectroscopy, Spectral line, 0103 physical sciences, Atomic physics, Nuclear Experiment, Spectroscopy, 010303 astronomy & astrophysics, Beam (structure)
Abstract

In-beam conversion electron spectroscopy experiments have been performed on the transfermium nuclei 253,254No using the conversion electron spectrometer SACRED in nearly collinear geometry in conjunction with the gas-filled separator RITU at the University of Jyvaskyla. The experimental setup is discussed and the spectra are compared to Monte Carlo simulations. The implications for the ground-state configuration of 253No are discussed.

Published
2002

9. Nuclear structure and formation mechanism of heavy shell-stabilized nuclei

Author

Andreas Martin Heinz, J. A. Cizewski, Kai Vetter, R. V. F. Janssens, M. Leino, P. Bhattacharyya, P. Reiter, G. D. Jones, John P. Greene, T. Lauritsen, C. N. Davids, H. Kuusiniemi, C. J. Lister, Juha Uusitalo, A. J. Chewter, I. Wiedenhöver, A. A. Sonzogni, Heikki Kettunen, F. G. Kondev, Sunniva Siem, K. Helariuta, P. A. Butler, D. Seweryniak, M. P. Carpenter, T. L. Khoo, R. Julin, H. Kankaanpää, Paul Greenlees, R.-D. Herzberg, and Iftikhar Ahmad

Subjects
Nuclear reaction, Physics, Neutron emission, Excited state, Nuclear Theory, Binding energy, Nuclear binding energy, Nuclear fusion, Neutron, Nuclear drip line, Atomic physics, Nuclear Experiment
Abstract

In a series of experiments, 48Ca induced cold fusion reactions on Pb targets were employed to populate states in 253,254No isotopes. Evidence for decays from a rotational band built on a 7/2[624] configuration was obtained in 253No. The ground-state band of 254No is identified up to spin 20+. The deduced quadrupole deformation is β=0.27(2). The initial angular momentum and excitation energy of 253,254No residues, after neutron emission, was determined. States up to spin 22ℏ and excitation energy of E*=8.5 MeV were observed. The data provide direct information on the fission barrier at high spins Bf⩾5 MeV, and on the shell-correction energy Eshellexp⩾4.1 MeV.

Published
2002

10. Spectroscopy of transfermium nuclei: 102252No

Author

W. H. Trzaska, W. Korten, K. J. Eskola, M. Houry, K. Helariutta, Heikki Kettunen, T. L. Khoo, N. J. Hammond, H. Kankaanpää, P. A. Butler, A. J. Chewter, F. P. Heßberger, J. Gerl, J. F. C. Cocks, Y. Coz, C. Scholey, R.-D. Herzberg, H. J. Wollersheim, Paivi Nieminen, S. Juutinen, C. J. Lister, Juha Uusitalo, M. Muikku, P. Reiter, N. Amzal, Peter B. Jones, M. Leino, P. Rahkila, Pasi Kuusiniemi, Paul Greenlees, R. Julin, R. D. Page, R. Lucas, K. Hauschild, O. Stezowski, Ch. Schlegel, F. Becker, O. Dorvaux, G. D. Jones, and Ch. Theisen

Subjects
Nuclear physics, Physics, Nuclear and High Energy Physics, Atomic physics, Spectroscopy
Published
2001

11. HIGH-SPIN STRUCTURE OF SOME NEUTRON-RICH ODD-<font>Z</font> NUCLEI WITH <font>A</font> ≈ 100 FROM HEAVY-ION INDUCED FISSION

Author

G. Duchêne, N. Redon, P. Petkov, Ts. Venkova, M. G. Porquet, A. Bauchet, A. Nowak, T. Kröll, A. J. Chewter, Stephane Perries, E. Piasecki, W. Urban, Matthias Meyer, R. Cunningam, I. Deloncle, M. Houry, N. Amzal, C. M. Petrache, R. Herzgerg, P. A. Butler, B. J. P. Gall, N. Schulz, Josette Duprat, S. Courtin, R. Lucas, N. Buforn, F. Hoellinger, A. Minkova, and A. Astier

Subjects
Physics, Fission, Neutron, Heavy ion, Atomic physics, Spin structure
Published
2001

12. First observation of excited states in the neutron deficient nuclei164Osand166Os

Author

S. L. King, D. M. Cullen, A. J. Chewter, J. Simpson, A. Keenan, S. Juutinen, O. Dorvaux, M. Muikku, R. D. Page, Paivi Nieminen, Roy Crawford Lemmon, Peter B. Jones, Paul Greenlees, A. Savelius, M. B. Smith, N. Amzal, Juha Uusitalo, K. Helariutta, H. Kankaanpää, Heikki Kettunen, Michael Taylor, Matti Leino, S. L. Shepherd, D. T. Joss, Pasi Kuusiniemi, R. Julin, and J. F. C. Cocks

Subjects
Nuclear physics, Physics, Nuclear and High Energy Physics, Excited state, Neutron, Atomic physics
Published
2000

13. Structure and formation mechanism of the transfermium isotope [sup 254]No

Author

J. P. Greene, J. A. Cizewski, A. J. Chewter, T. L. Khoo, D. Seweryniak, I. Wiedenhöver, M. Alcorta, Kai Vetter, A. A. Sonzogni, M. P. Carpenter, T. Lauritsen, P. T. Greenlees, G. D. Jones, N. Amzal, P. A. Butler, I. Ahmad, C. J. Lister, J. D. Fox, R. V. F. Janssens, N. Fotiades, P. Reiter, R-D Herzberg, G. Gervais, D. Sullivan, W. Korten, W. F. Henning, J. Uusitalo, C. N. Davids, M. Leino, K. Y. Ding, and S. Siem

Subjects
Physics, Isotope, Fission, Nuclear Theory, Nuclear structure, Deformation (meteorology), medicine.anatomical_structure, Quadrupole, medicine, Nuclear fusion, Atomic physics, Nuclear Experiment, Nucleus, Spin-½
Abstract

The ground-state band of the Z=102 isotope 254No has been identified up to spin 14, indicating that the nucleus is deformed. The deduced quadrupole deformation, β=0.27, is in agreement with theoretical predictions. These observations confirm that the shell-correction energy responsible for the stability of transfermium nuclei is partly derived from deformation. The survival of 254No up to spin 14 means that its fission barrier persists at least up to that spin.

Published
1999

14. Excited states in the heavy nuclide [sup 254]No

Author

Heikki Kettunen, W. H. Trzaska, P. A. Butler, F. Becker, P. Reiter, W. Korten, H. Kankaanpää, A. Savelius, J. F. C. Cocks, O. Dorvaux, J. Gerl, A. J. Chewter, M. Houry, Ch. Schlegel, Ch. Theisen, T. L. Khoo, H. J. Wollersheim, A. Kleinböhl, R. D. Page, P. Rahkila, Y. Le Coz, R. Lucas, S. Juutinen, Peter B. Jones, M. Muikku, Paul Greenlees, K. J. Eskola, K. Helariutta, G. D. Jones, Pasi Kuusiniemi, R. Julin, R.-D. Herzberg, M. Leino, Paivi Nieminen, and F. P. Heßberger

Subjects
Nuclear physics, Physics, Fission, Excited state, Quadrupole, High Energy Physics::Experiment, Gamma spectroscopy, Alpha decay, Nuclide, Atomic physics, Nuclear Experiment, Ground state, Spectroscopy
Abstract

In-beam γ-ray spectroscopy of the excited states in the heavy nuclide 254No have been studied in the reaction 208Pb(48Ca,2n)254No. The techniques of recoil-gating and recoil-decay-tagging were needed due to the dominant fission background. Prompt γ-rays were detected with a Ge detector array, consisting of four clover detectors in close geometry, and a gas-filled recoil separator (RITU) was used for detecting recoils and their α-decays. The observed six γ-rays were associated with E2-transitions in the ground state rotational band of 254No. The value β2=0.27±0.03 was extracted for the quadrupole deformation from the extrapolated 2+ excitation energy.

Published
1999

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