Some boundary phenomena in heavy ion physics: nuclear calefaction and high excitation fission
Description
In this work we investigate new phenomena which can be observed in Heavy Ion reactions at bombarding energies between 20 and 50 MeV/u. In reactions induced by a Kr beam at 35 and 22 MeV/u we have found fragments with a kinetic energy and a mass substantially smaller than the one of the projectile. We propose a possible interpretation for their occurrence: they could be produced in a kind of nuclear calefaction phenomenon. Such a mechanism would take place because of the mean field which still plays an important role at these bombarding energies and which modifies the usual participant-spectator picture familiar at higher bombarding energies. The stability against fission of the high temperature and rapidly rotating nuclei produced in such reactions is then studied within the framework of the Thomas Fermi and Hartree Fock approximations. The fission barrier decreases with increasing temperature and angular momentum and the stability limit of the 205At nucleus is investigated. (author)
Abstract (French)
Cette these porte sur les phenomenes nouveaux qu'il est possible d'observer dans les reactions d'ions lourds dans la region de transition, 20 a 50 MeV/nucleon. Nous avons detecte dans les reactions induites par un faisceau de krypton a 35 et 22 MeV/nucleon des fragments ayant des masses et des energies cinetiques tres inferieures a celles du projectile. Une interpretation pos sible de ces resultats inclusifs est proposee: ils peuvent provenir d'un phenomene de calefaction nucleaire. Ce mecanisme aurait lieu par la persistance de l'effet du champ moyen a ces energies qui modifie l'image participants-spectateurs familiere a plus haute energie. La stabilite des noyaux a haute temperature et grand moment angulaire que l'on peut former dans de telles collisions est ensuite etudiee par rapport au procesus de fission dans le cadre des approximations Thomas Fermi et Hartree Fock quand la temperature et le moment angulaire augmentent. La limite de stabilite par rapport a la fission de l'205At est calculee en fonction de ces parametres. (auteur)Files
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Additional details
Additional titles
- Original title (French)
- Quelques phenomenes frontieres en physique des ions lourds: calefaction nucleaire et fission a haute excitation
Identifiers
Publishing Information
- Imprint Pagination
- 157 p.
- Report number
- FRCEA-TH--6259
INIS
- Country of Publication
- France
- Country of Input or Organization
- France
- INIS RN
- 46040642
- Subject category
- S73: NUCLEAR PHYSICS AND RADIATION PHYSICS;
- Resource subtype / Literary indicator
- Thesis
- Quality check status
- Yes
- Descriptors DEI
- ANGULAR MOMENTUM; ASTATINE 205; BINDING ENERGY; EVAPORATION MODEL; EXCITATION; FISSION BARRIER; HARTREE-FOCK METHOD; HEAVY ION REACTIONS; HOT NUCLEI; IONIZATION CHAMBERS; KRYPTON 84 BEAMS; NEODYMIUM 144; NUCLEAR FRAGMENTS; QUADRUPOLE MOMENTS; ROTATION; TEMPERATURE DEPENDENCE; THOMAS-FERMI MODEL; VELOCITY
- Descriptors DEC
- ALPHA DECAY RADIOISOTOPES; APPROXIMATIONS; ASTATINE ISOTOPES; ATOMIC MODELS; BEAMS; BETA DECAY RADIOISOTOPES; BETA-PLUS DECAY RADIOISOTOPES; CALCULATION METHODS; ELECTRON CAPTURE RADIOISOTOPES; ENERGY; ENERGY-LEVEL TRANSITIONS; EVEN-EVEN NUCLEI; HEAVY NUCLEI; INTERMEDIATE MASS NUCLEI; ION BEAMS; ISOTOPES; MATHEMATICAL MODELS; MEASURING INSTRUMENTS; MINUTES LIVING RADIOISOTOPES; MOTION; NEODYMIUM ISOTOPES; NUCLEAR MODELS; NUCLEAR POTENTIAL; NUCLEAR REACTIONS; NUCLEI; ODD-EVEN NUCLEI; POTENTIAL ENERGY; POTENTIALS; RADIATION DETECTORS; RADIOISOTOPES; RARE EARTH NUCLEI; YEARS LIVING RADIOISOTOPES
Optional Information
- Notes
- 90 refs.; Available from the INIS Liaison Officer for France, see the 'INIS contacts' section of the INIS website for current contact and E-mail addresses: http://www.iaea.org/inis/Contacts/