Table Of ContentLecture Notes
ni Physics
Edited by .J Ehlers, M~nchen, .K Hepp, Z~irich,
.R Kippenhahn, M{Jnchen, .H A. WeidenmLiller, Heidelberg,
and .J Zittartz, KSIn
Managing Editor: W. Beiglb6ck, Heidelberg
16
ml
Photonuclear Reactions I
International School on Electro- and
Photonuclear Reactions,
Erice, Italy 1976
Edited by S. Costa and C. Schaerf
Springer-Verlag
Berlin. Heidelberg • New York 1.977
Editors
Prof. Sergio Costa
Instituto di Fisica, Universita di Torino
Corso M. d'Azeglio, 46
10125 Torino, Italia
Prof. Carlo Schaerf
Instituto di Fisica, Universita di Roma
Piazzale delle Scienze, 5
00185 Roma, Italia
Library of ssergnoC Cataloging in Publication Data
International School on Electro and Photonuclear Reac-
tions, Erice, Italy, 1976.
Phot onuc r~eel reaction8.
(Lecture notes in physics ; 61-62)
i. Photonuclea~ reactions--Congresses, 2. Electro-
magnetic interactions--Congresses. I. Costa, Sergio.
II. Schaerf, Carlo, 1935- ~II. E~tore ~Jorana
Centre for Scientific Culture. IV. Title. .V Series.
Q079~.8. P4155 1976 539.7'~6 77-~56
ISBN 3-540-08139-9 Springer-Verlag Berlin Heidelberg New York
ISBN 0-387-08139-9 Springer-Verlag New York Heidelberg Berlin
This work is subject to copyright. All rights are reserved, whether the whole
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© by Springer-Verlag Berlin • Heidelberg 1977
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215313140-543210
PREFACE
Our understanding of the nature of fAmdamental interactions has been greatly
helped by experiments involving electrons and photcns. These tools had, and still
have, indeed, a relevant impact on the investigation of atc~ and molecules, as
well as nuclear structure.
In the case of nuclear systems held together by forces not yet completely
understood, the electrcmagnetic probes, whose interaction with the nucleons in the
nucleus is basically well known, provided us with matrix elements giving direct
information on the nuclear wave functions.
The study of the electrcmagnetic porperties of nuclear states has been crucial
for the development of nuclear models andt he good knowledge of the quantum numbers
associated with specific multipoles has notably simplified the analysis of the
fundamental types of nuclear motion.
A large number of laboratories are currently carrying out experiments using
both electron and real photon beams and, in many of these, a noticeablee ffort is
being made to improve the quality of the existing ins~tation, as well as to
set up new facilities.
The purpose of the School on Electro- and Photonuclear Reactions ,si there-
fore, to review and discuss the most significant achievements in the study of
nuclear properties using electromagnetic probes with special emphasis on the most
recent experimental and theoretical results obtained in this field.
Because of the vastness of the subject, the first course of the School was
essentially devoted to photonuclear interactions from few MeVu p to intermediate
energy.
Ten series of lectures (collected in Volume )I and a ntm~er of seminars were
given. Most of the seminars were presented in the form of status reports from
important laboratories, and these reports are collected in V~It~e .II
In the lecture sessions, the classic topic of the giant dipole resonance
was first reviewed and the phencmenology discussed together with the mechanisms
leading to the excitation of the giant states. Collective anmdi croscx~ic models
were proposed ionr der to push the theoretical description closer to the experi-
mental results. Isotopic spin effects and sum rules ccmpleted the study of the
doorway states through which the G.D.R. is formed.
The competition betweent he decay channels from the G.D.R. was analysed and
the existing knowledge of MI and E2 resonances, both isoscalar and isovector, was
surveyed.
Nuclear elastic photon scattering %~s discussed in detail, including the
contributioofn s Thcmson, Rayleigh and Delbruck scattering. Suggestions for
future experimentation, mainly with polarized photons, were also made.
A nweawy of calculating the transition matrix at intermediate energy was
presented, underlining the relevance of gauge terms and describing the direct
coupling of the photon to nucleon-nucleon correlations.
Exchange-current p h ~ were alsdoi scussed in connection with the
integrated photo-absorption cross section, which is shown to contain information
on mesonic degrees of freedom in nuclei. The effects of explicitly introducing
isobars on nuclear constitutents were explored, in particular, in the case of
electrQmagnetic interactions in the two-nucleon system.
Finally the few-body systems and their interaction with real avnidr tual
photons and with hadrons were discussed as a check of our present understanding
of nuclear propertieisn terms of the basic n-n force.
During the course special theoretical topics were introduced by same partici-
pants:these are also sum~rized in Volt~e .II
The course could have not been so rewarding as it was without the
enthusiastciocl laboration of all the lecturers and participants andt he entire
staff of the Centro di Cultura Scientifica Ettore Majorana . It is a pleasure
to thank in particular Prof. .A Zichichi, Director of the Centre, .rD S.A. Gabriele,
Miss .P Savalli and Miss .M Zaini for their generous help.
The organization of the course was made possible by the financcioanlt ributions
of thNea tional Research Council (CNR) and the National Institute of Nuclear Physics
.)NFNI( We wish etxop ress our gratitude to Prof. .E Amaldi, President of the
National Ccmmittee for the Physical Sciences of RqIC and Prof. .A Gigli, President
of INFN.
TABLE OF C C ~
LECTURES
/
BERGERE, R. : Features of the Giant EI Resonance ......................... ~ ¢
RICCO, .G Photonuclear Reactions above the Giant Dipole Resonance. /
A Survey ................................................... 223
HANNA, S. ; Giant ~llt/pole Resonances ................................. 275/
HA~ARD, .E ; Photon Scattering in the Energy Range 5-30 V~%~ ........... ~40 /
HEBACH, .H ; ~zhanisms of Photonuclear Reactions at Intermediate /
Energies 04( - 140 MeV) ................................... 407
BOSCO, .B : Real and Virtual Photons ................................... ~451 /
!
WEISE, ~. : Sum Rules in P~tonuclear Physics .......................... ~ /
~ I , .R : Isospin Structure of the Dipole Giant Resonance ......... 501/
CIOFI DEGLI ATTI, .C : Electromagnetic aD~ M~dronic Interactions with
the Few-Body Systems at Intermediate Energies ... 521 /
~UVEL, .H : Bayron Resonances in Nuclei 586 /
TABLE OFCCNZ~fS
(to emuloV II)
INVITED S~INARS
BERIDZZI, W. : Recent Developments at M.I.T .............................. 1
CATI~, Ph. : News from Saclay ........................................ ~7
DE VRIES, C. : Electron Scattering Work at Amsterdam - past, present
and future activities .................................... 62
92
D~EL, D. : Electronuclear Sum Rules .................. : ..............
LINDGIR~, K. : A Review of Present Photonuclear Research at Lund and
future Accelerator Plans ................................. 132
MATONE, G. A ~ncchromatic and Polarized Photon Beam for Photo-
nuclear Reactions, The T~don Project at Frascati ........... IZ~9
RICHTER, A. : Latest from Dalinac ....................................... 165
SANZONE, M. : Preliminary Results on the Annihilation Photon Beam at
199
the Frascati Linac laIx)ratory .............................
SOLODUKHOV, G.V. : Some Experimental Results on the Measurement of the
the total Photoabsorption Cross Sections ............. 216
TORIZUKA, Y. : Electroexcitation of Giant ~/itipole Resonances .......... 2~8
CF CONTRIBUTED S~7qARS
29~
BCI41GAS, O. : Description of Isoscalar Resonances. A ~10proach StIn-Rule ..
295
DELSANTO, P.P. : The Center of Mass Problans in ContinutIn ...............
297
GIANN~I,M. : A Sinple Model for Resonance Shifts ......................
P~P~,D. : Nucleon Polarizabilities and Deep Inelastic Electron
Scattering ............................................... 298
,NT.T.TTTSIRHC P. and ROSA-CIET, M. : Exchange Effects in Photon
Scattering in Nuclei ................. 301
List of Participants
ARENHOEVEL, H., Mainz JOHNSSC~, B., Lund
BERGERE, ,.R Bures sur Yvette ,HC%~d~E'iUAI C., Garching
BEEIDZZI, W., Cambridge (USA) LEONARDI, ,.R Bologna
BC~IGAS, O., Orsay L~I'F~, A., Gif sur Yvette
BOSO0, B., Arcetri LINDGREN, ,.K Lur~
CALOI, ,.R Rsma I/PPARINI, E., Trento
CARCHCN, ,.R Gent MATC~E, G., Frascati
CATILI£~, p., Gif sur Yvette ~ S , J.L., Cambridge (USA)
CH~7, S.H., Birmingham MBCKING, B., Bonn
CIOFI DEGLI ATTI, C., anrcR PANTALEO, A., Bari
COSI~, S., Torino PROSPERI, D., Frascati
DEI2ANTO, P.P., Cagliari RICCO, G., Genc~a
D'ERASM0, ,.G Bari RIC~IER, A., Darmstadt
DEVOS, J., Gent ROSA-CIDT, M., Geneva
DE ~ , C., Amsterdam ROSS, C., Ottawa
DREC}~EL, ,.D Mainz SANZGNE, M., Genc~a
EPPEL, D., Hamburg SCHAERF, ,.C Ruma
FABRE DE LA RIPELTR, M., Orsay ,V)KIKUDEKCS G.V., Mosccw
FINDIAY, D.J.S., Glasgow STRANGIO, C., Rcma
GIANNINI, M., Genova TERRANOVA, M.L., R0ma
GIUSTI, ,.C Pavia TORIZUKA, Y., Sendai
GC~RINGER, H., Mainz TRAINI, M., Trento
HA~mA, S.S., Stanford (U~) VAN CAMP, E., Gent
HA~/~, E., Washington, DC ,ESI~.T W., Erlangen
HEBACH, H., Bocht~n ,CENYL)K~ E., Sao Paulo
FEATURES OF THE GIANT - E I RESONANCES
R. BERGERE
D4partement de Physique
Nucl4aire
CEN/ SACLAy
INTRODUCTION
CHAPTER I : THE GIANT MULTIPOLE RESONANCES
I.A. What is a so called Giant Resonances ?
I.B. A brief classification of the Giant Resonances.
I. B. 1 Isoscalar giant resoances.
I. B. Z Compression modes.
I.B.3 Polarization modes.
I.C. Excitation of a Giant l~esonance mode .
I.C.I. Real photon induced reactions,
I.C,Z, Radiative capture (p,7), .)7,~c(
I.C.3. electrons. scattering of Inelastic
I.C.4, Inelastic scattering of hadrons.
I.C.5. Muon capture.
.I C. .6 Pion radiative capture.
.I C. .7 Virtual excitatlons.
CHAPTER II : THE PHOTON BEAMS
.I Photons produced in nuclear excitations.
I.A. ,p( ) 7 sources.
I.B. (n,y) sources
I.B.I. Photons sources with discrete energies.
I. B. 2. Compton scattering of neutron capture y.
I. B. 3. Nuclear resonance scattering.
I.C. Nuclear resonance scattering of Bremstrahlung ¥.
.../..
.II Bremstrahlung photon beams.
II.A. Useofthe pit of Bremstrahlung spectra.
.11 B. Total absorption experiments.
.II C. Tagged photon beams.
.II D. Unfolding of Bremstrahlung yield data.
.11I Monochromatic photon beams with variable energy.
CHAPTER III : THE COLLECTIVE MODELS OF THE El
GIANT P~ESONANCE
III.A. The nucleon effective charges.
.III B. The static collective model for spherical nuclei.
.III B. .1 The Ooldhaber - Teller model.
.111 B.Z. The Steinwedel - Jensen model.
.111 B. .3 Comparison with experimental data.
111.B. .4 Refinements of the theoretical prediction .
a) consideration of a realistic nuclear surface
b) introduction of a variable K.
.111 C. The static collective model for permanently deformed nuclei.
.III C. ,I The 3( 0 splitting,
.11I C.Z. The Lorentz llne .tif
.llI C, .3 Comparison with experimental data.
.111 D. The dynamic collective model.
.111 D. .1 The dynamic collective model for vibrationnnaulc lei
a) theoretical summary
b) comparison with experimental data :
- Sn isotopes
-Te, Cd, Pd
- Nd isotopes
- general features of experimental data.
HI. D.Z. The improved dynamic collective model
a) theoretical summary
b) comparison with experimental data :
transition region around N = 89
-
transition region around A --190
-
CHAPTE1% IV : THE IV[IC1%OSCOPIC MODELS OF THE EI
GIANT RESONANCE
IV.A. The schematic model of Brown - Bolsterli.
IV.B. Effective h p I - i calculations of the G.D.1%. for closed
shell nuclei
)l 061
)z z°spb.
IV. C. Effective h p 1 - 1 calculations tohfe GDIq. for non closed
shell nuclei.
IV.D. h p self 1 - 1 consistent models of the GDR.
IV.E. The h p 1 - i continuum models of the GDR.
IV. F. Consideration of np - nh states in the fine structure of the GDR
IV.F.I. Coupling of the h p 1 - 1 dipole state ot the first low
energy Z+state.
IV. F. 2. The effect of the quasi bound states.
IV.F.3. A p 3 - h 3 model for the GDR of 160.
IV.F.4. The fine structure of the GD1% as a consequence of the
"nuclear coexistence".
IV. O. A microscopic description of the damping width,
IV.H. The microscopic models of the sum rules
IV. H. .I The energy weighted sum- rule 0 O
IV. H. 2. The Bremstrahlung weighted sum-rule i_7(
IV.H. .3 2- suTmh-e a rule.
