Exotic Nuclear Spectroscopy

660 Pages·1990·22.68 MB·English

by  Peter E. Haustein (auth.), William C. McHarris (eds.)

Exotic Nuclear
Spectroscopy
Exotic Nuclear
Spectroscopy
Edited by
William C. McHarris
Michigan State University
East Lansing, Michigan
u.e
Springer Science+ Business Media,
Llbrary of Congress Catalog1ng-ln-Publ1catlon Data
Symposium an Exotic Nuclear Spectroscopy (1989 Miami Beach, Fla.1
Exotic nuclear spectroscopy ! edited by Willlam C. McHarris.
p. cm.
'Proceedings of an American Chemical Society Dlvislon of Nuclear
Chemistry and Technology Symposium an Exotic Nuclear Spectroscopy,
held September 11-15, 1989, in Miami Beach, Florida'--T.p. versa.
Includes bibliographical references and index.
ISBN 978-1-4613-6637-9 ISBN 978-1-4615-3684-0 (eBook)
DOI 10.1007/978-1-4615-3684-0
1. Nuclear spectroscopy--Congresses. 1. McHarris, Wi 11 iam C.
II. American Chemical Society. Division of Nuclear Chemlstry and
Technology. III. Title.
OC454.N8S96 1989
543' .0858--dc20 91-8182
CIP
Proceedings of an American Chemical Society Division of
Nuclear Chemistry and Technology Symposium on Exotic
Nuclear Spectroscopy, held September 11-15, 1989,
in Miami Beach, Florida
© 1990 Springer Science+Business Media New York
Originally published by Plenum Press in 1990
Softcover reprint of the hardcover 1s t edition 1990
AII rights reserved
No part of this book may be reproduced, stored in a retrieval system, or transmitted
in any form or by any means, electronic, mechanical, photocopying, microfilming,
recording, or otherwise, without written permission from the Publisher
Preface
Several hundred nuclear scientists from more than a dozen countries met in Miami Beach,
Florida, in September 1989 for a Symposium on Exotic Nuclear Spectroscopy, sponsored by
the Division of Nuclear Chemistry and Technology of the Amencan Chemical Society.
Braving five days of beckoning beaches, they presented, listened to, and discussed a series
of invited papers covering the renaissance of nuclear spectroscopy-both experimental and
theoretical-that has occurred during the past decade and which promises to continue well
into the decade to come. This book contains the Proceedings of that Symposium on Exotic
Nuclear Spectroscopy. But it is much more: During the ensuing six months, most of the
pa{>ers were rewritten, polished, and/or expanded; so the resulting book is a much more
fimshed, comprehensive, and up-to-date product than a general proceedings.
Chapter se~uences follow the original symposium program, which, with a few exceptions,
juxtaposes like topics. Each chapter can stand more or less on its own-although, as in any
complex, interrelated scientific field, there are many cross-references among chapters.
The manuscripts were edited and then uniformly typed in the Department of Chemistry at
Michigan State University. I tried to keep the editing to a minimum so as to preserve the
flavor of individual styles.
A great debt of gratitude goes to those who helped make this volume possible, especially to
Vada O'Donnell, who bore the largest burden of typing (and clarifying) the manuscripts.
Special thanks also goes to the Division of Nuclear Chemistry and Technology of ACS for
its financial and moral support-J. Robb Grover, who as Chairman of the Division
initiated the project, worked especially hard to help bring it about. And, finally, I thank the
forty-one authors (or sets of authors) who took time out of their busy schedules to come to
Miami Beach for their presentations, then took even more time out of increasingly busy
schedules to write the finished papers. I hope and think this volume should be a useful
reference for the next few years, indicating, as it does, the directions nuclear spectroscopy
-and almost all nuclear spectroscopy nowadays can qualify as "exotic"-seems to be
taking.
Wm. C. McHarris
East Lansing, Michigan
July 1990
Contents
1. Atomic Mass Measurements with Radioactive Beams and/or Targets:
Where to Start 1
P. E. Haustein
2. A Recoil Mass Spectrometer for the HHIRF Facility 11
J. D. Cole, T. M. Cormier, and J. H. Hamilton
3. The Study of Exotic N '" 82 Nuclei Using the Daresbury Recoil Mass
Separator 23
J. H. McNeill, A. A. Chishti, W. Gelletly, M. A. C. Hotchkis, B. J.
Varley, J. Blomqvist, P. J. Daly, M. Piiparinen, and P. J. Woods
4. Spectroscopic Techniques in the Study of Radioactive Nuclei Far from
Stability: Results for the Z = 82 Region 39
E. F. Zganjar, J. L. Wood, and J. Schwarzenberg
5. Nuclear Decay Studies Far from Stability 57
R. B. Firestone, J. M. Nitschke, P. A. Wilmarth, K. S. Vierinen,
R. M. Chasteler, J. Gilat, and A. A. Shihab-Eldin
6. Accelerated Radioactive Nuclear Beams (Low Energy) 83
John M. D'Auria
7. A Technique for Proton Drip-Line Studies via Fusion-Evaporation
Reactions 101
M. F. Mohar, W. Benenson, D. J. Morrissey, R. M. Ronningen, B.
Sherrill, J. Stevenson, J. S. Winfield, J. Yurkon, J. Garres, and K.
Subotic
8. Nuclear Structure in the Neutron-Rich Doubly-Magic 78Ni Region 111
John C. Hill, F. K. Wohn, J. A. Winger, E. K. Warburton, R. L.
Gill, and R. B. Schuhmann
9. Nuclear Spectroscopy in the Rare-Earth Region Near the Proton
Drip Line 127
K. S. Toth, J. M. Nitschke, P. A. Wilmarth, and K. S. Vierinen
vii
viii CONTENTS
10. Shapes and Moments of Odd-A Pt Nuclei (177,,;A,,; 195) 139
J. Rikovska
11. Towards Superheavy Nuclei-Status and Prospects for the Production
and Investigation of Heavy Elements 181
G. Miinzenberg and P. Armbruster
12. Reflection-Asymmetric Shapes in Nuclei 205
I. Ahmad, M. P. Carpenter, H. Emling, R. Holzmann, R. V. F.
Janssens, T. L. Khoo, E. F. Moore, L. R. Morse, J. L. Durell,
J. B. Fitzgerald, A. S. Mowbary, M. A. C. Hotchkiss, W. R. Phillips,
M. W. Drigert, D. Ye, and Ph. Benet
13. Reflection Asymmetry and Fission Yields in the Mass-145 Region and a
Possible Route to Superheavy-Element Synthesis 217
J. D. Robertson and W. B. Walters
14. Quadrupole and Octupole Shapes in Nuclei 229
D. Cline
15. GAMMASPHERE 245
I.-Y.l.ee
16. Evidence for Octupole-Octupole and Quadrupole-Octupole Excitations in
Spherical Nuclei 259
S. W. Yates, R. A. Gatenby, E. M. Baum, E. L. Johnson, J. R.
Vanhoy, T. Belgya, B. Fazekas, and G. Molnar
17. Spin-Stabilized Deformation in Transitional Nuclei 271
P. Chowdhury, B. Crowell, P. J. Ennis, C. J. Lister, Ch. Winter,
H. R. Andrews, D. Horn, D. C. Radford, D. Ward, J. K. Johansson,
J. C. Waddington, and S. Pilotte
18. Shape Evolution Studies in the A = 70 Region 283
A. V. Ramayya and J. H. Hamilton
19. Shape and Structural Changes in Nuclei at High Spin and Temperature 293
T. L. Khoo, I. Ahmad, R. Holzmann, R. V. F. Janssens, E. F.
Moore, F. L. H. Wolfs, M. W. Drigert, K. B. Beard, D.-Z. Ye,
U. Garg, Ph. Benet, P. J. Daly, and Z. Grabowski
20. Shell-Model Calculations for Exotic Nuclei 295
B. A. Brown, E. K. Warburton, and B. H. Wildenthal
21. Recent Results on Superdeformation 321
M.-A. D. Deleplanque
22. Nuclear Collectivity and Complex Alignment Mechanisms in Light W
and Os Nuclei 339
N. R. Johnson
CONTENTS ix
23. Discrete-Line Spectroscopy in Superdeformed Nuclei 355
V. P. Janzen, J. K. Johansson, J. A. Kuehner, D. Radford,
J. C. Waddington, D. Ward, and the 8". Collaboration
24. High-Spin Properties of Doubly-Odd Nuclei of Mass", 130 369
E. S. Paul, C. W. Beausang, D. B. Fossan, Y. Liang, R. Ma,
W. F. Piel, Jr., S. Shi, and N. Xu
25. Rotational-Band Structure in Odd-Odd Re Nuclei 379
W. A. Olivier, W.-T. Chou, A. Rios, W. C. McHarris,
and R. Aryaeinejad
26. Double Decoupling in Deformed Doubly-Odd Nuclei 393
A. J. Kreiner
27. Deformed Odd-Odd Nuclei: Matrix Elements for the Residualp-n Interaction
and Patterns of Alternating Perturbations in Level Spacings 413
R. W. Hoff, A. K. Jain, J. Kvasil, P. C. Sood, and R. K. Sheline
28. Proton-Neutron Interactions in the A = 100 Nuclides 427
R. A. Meyer, I. Morrison, and W. B. Walters
29. Dynamical Symmetries for Fermions 437
M. Guidry
30. Particles as Probes of Nuclear Shape in the Rare Earths and Structure
Q
Effects on Proton Emission in the Mass-80 Region 457
D. G. Sarantites, N. G. Nicolis, V. Abenante, Z. Majka, T. M.
Semkow, C. Baktash, J. R. Beene, G. Garcia-Bermudez, M. L.
Halbert, D. C. Hensley, N. R. Johnson, I.-Y. Lee, F. K. McGowan,
M. A Riley, A Virtanen, and H. C. Griffin
31. Fast f3 Transitions and Intrinsic Structures in Deformed Nuclei 473
P. C. Sood and R. K. Sheline
32. Intruder States, Coexistence, and Approaches to Deformation:
The Study of 120Xe and the N = 66 Isotones 495
P. F. Mantica, Jr., B. E. Zimmerman, C. E. Ford, W. B. Walters, D.
Rupnik, E. F. Zganjar, H. K. Carter, J. Rokovska, and N. J. Stone
33. Global Trends and Structural Consequences of the Proton-Neutron
Interaction 511
D. S. Brenner, R. F. Casten, C. Wesselborg, D. D. Warner,
and J.-Y. Zhang
34. IBFFA Calculations of Odd-Odd Nuclei 523
W.-T. Chou, W. C. McHarris, and O. Scholten
CONTENTS
x
35. Delayed-Neutron Emission Probabilities of Li-F Nuclides 535
P. L. Reeder, R. A. Warner, W. K. Hensley, D. 1. Vieira,
and 1. M. Wouters
36. Exotic Decays at the Proton Drip Line 549
D. M. Moltz, T. F. Lang, 1. Cerny, 1. D. Robertson, and 1. E. Reiff
37. Delayed Fission of Light Am Isotopes 561
H. L. Hall and D. C. Hoffman
38. High-Spin Spectroscopy for Odd-Z Nuclei with A '" 160 587
c.-H. Yu, 1. Gascon, G. B. Hagemann, and 1. D. Garrett
39. Fast Chemical Separations for the Study of Short-Lived Nuclides 609
K. Rengan
40. Rotational Population Patterns and Searches for the Nuclear SQUID 625
L. F. Canto, R. 1. Donangelo, A. R. Farhan, M. W. Guidry, 1. O.
Rasmussen, M. A. Stoyer, and P. Ring
41. Time-Resolved and Time-Integral Studies of Nuclear Relaxation: 637
An Extension of the On-Line Nuclear Orientation Technique to Shorter
Half-Lives
N. 1. Stone
42. Exotic Nuclear Spectroscopy-Remembrance of Past Futures 657
Wm. C. McHarris
Author Index 665
Nuclide Index 667
Subject Index 673
1. Atomic Mass Measurements with Radioactive Beams
and/o r Targets: Where to Start
Peter E. Haustein
Department of Chemistry
Brookhaven National Laboratory
Upton, NY 11973 USA
ABSTRACT
Radioactive beams or radioactive targets (or both) can significantly increase the yields of ex·
otic isotopes, allowing studies to be performed in regions which are currently inaccessible. An
important goal to pursue with these exotic species is a broad program of nuclidic mass mea
surements. This is motivated by the observation that mass-model predictions generally diverge
from one another in regions far from f3 ·decay stability where well-measured masses are sparse
or nonexistent. Stringent tests of mass models are therefore possible, and these can highlight
important features in the mass models that affect the quality of their short-range and long
range extrapolation properties. Selection of systems to study can be guided, in part, by a de
sire to probe those regions where distinctions among mass models are most apparent and
where exotic isotope yields will be optimal. Several examples will be presented to highlight
future opportunities in this area.
1.1 INTRODUCTION
Nuclei far from stability have traditionally been a fertile ground for tests of models
of nuclear structure, nuclear masses, and for the discovery of new nuclear decay modes and
structural dynamics. Several illustrative examples are: (super)-deformation regions and
shape evolution; fissility variation and fission modes; f3 -delayed particle emission; direct
proton radioactivity; synthesis of the heaviest elements; and the interplay between nuclear
decay properties and r- and rp-process nucleosynthesis.
One can confidently expect this to continue as new methods that employ radioactive
beams and/or radioactive targets allow even greater excursions to be made from the valley
of f3 stability. Indeed, the increase of available decay energy alone opens more exotic de
cay channels, many of which may prove to be the doorways to the study of new features of
nuclear structure.
It is instructive to look in detail at one selected area-masses of nuclei far from
stability. This is motivated by the fact that mass measurements of new nuclei were not part
of the database which had been used to refine the parameters used in the construction of
the mass model. Therefore, well-measured masses of these new nuclides serve as impartial
tests of the predictive quality among diverse sets of mass models. Such tests frequently
serve to identify "good" mass models, i.e., those models whose predictions on either a global
basis or in restricted mass regions prove to be of highest quality. Having identified a model
Exolic Nuclear Speclroscopy, Edited by W. C. Me Harris
Plenum Press, New York. 1990
2 P. E. Haustein
(or models) in this way, the selection of additional experiments can be guided with greater
assurance.
1.2 SHORT REVIEW OF MASS MODELS
A short review of the methods used in the construction of mass models is useful in
the context of the analysis which will follow. A more complete description of methods can
be found in the most recent compilation of mass-model predictions and related materiaJ.1
Construction of a mass model generally involves several steps. The model's basic content is
first selected, i.e., ab initio, phenomenological, semi-empirical, liquid drop(Iet), shell model,
or mass-relations based. The next step is the selection and evaluation of each mathemati
cal component of the model that is thought to characterize the relevant physical features of
the mass surface. From this step a prototype mass equation is generated. The third step
involves attempts to fit the prototype mass equations to the known mass surface. This gen
erally involves the use of iterative least-squares methods wherein mass equation terms and
their coefficients are adjusted to minimize residuals with respect to the body of known
masses. Once "best fit" parameters are obtained, the final step consists of the calculation of
predicted masses for the measured (input) masses and the calculation of predicted (output)
masses for isotopes beyond the known mass surface. This is done generally out to the neu
tron and proton drip-lines and into the region of superheavy elements, unless features of
the model preclude such calculations or there are reasons to believe that the predictions
become instrinsically unreliable in these regions.
1.3 CHARACTERISTICS OF MASS MODELS IN REGIONS WHERE
EXPERIMENTAL DATA EXIST
The "goodness of fit" of a particular model can be quantified by the average and
root-mean-square (rms) deviations of the predicted masses relative to the known masses.
Average deviation indicates whether, on a global basis, the calculation has predicted slight
over-binding or slight under-binding relative to the isotopic database. RMS deviation sig
nals the degree of conformation of the predicted mass surface to the measured one. In
general, smaller rms deviations are achieved through the use of larger numbers of ad
justable parameters in the models. An interesting correlation between the numbers of ad
justable parameters in mass models and the rms deviations of these models to the known
mass surface was noted by Tondeur.2 He observed that models which have most success
fully and proficiently incorporated the relevant physical features of mass surface achieve
the smallest rms deviations with a minimum number of adjustable parameters.
In the 1986-1987 Atomic Mass Predictions,! residuals for each mass model were
plotted in the format of the Chart of the Nuclides. This allows one to gauge the reliability
of the predictions in regions that border the experimentally known surface. The smallest
collections of residuals are generally associated with those models employing the largest
number of adjustable parameters. This does not necessarily mean that such models will
have the best extrapolation properties. Analyses3-5 of earlier (1975-81) sets of predic
tions6-9 showed that for those models there is only a rough correlation between the quality
of fits to the known mass surface and the quality of mass predictions for new isotopes that
were subsequently measured.