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Title: Prompt dipole {gamma}-ray emission: a new cooling mechanism in fusion heavy-ion reactions

Abstract

We investigated the prompt dipole {gamma}-ray emission, related with entrance channel charge asymmetry effects, in the 40Ar + 92Zr and 36Ar + 96Zr fusion-evaporation reactions at Elab= 15.1 and 16 MeV/nucleon, respectively, with the aim to probe its evolution with incident energy. These reactions populate, through entrance channels having different charge asymmetries, the same compound nucleus at an average excitation energy of 304 MeV with identical spin distribution. It was shown that the dipole {gamma}-ray intensity in the bremsstrahlung subtracted linearized spectra increases by {approx}14% for the more charge asymmetric system. This result, associated with those reported for the 32,36S + 100,96Mo reaction pair at lower beam energies, implies a ''rise and fall'' trend of the prompt dipole {gamma}-ray emission with beam energy with a maximum value at Elab= 9 MeV/nucleon.

Authors:
; ; ;  [1]; ; ; ; ;  [1];  [2]; ; ; ; ; ; ; ; ; ; more »;  [3];  [4] « less
  1. INFN, Sezione di Napoli, Naples (Italy)
  2. (Italy)
  3. Dip. di Fisica e Astronomia, Univ. di Catania, Catania (Italy)
  4. (Italy) (and others)
Publication Date:
OSTI Identifier:
21054815
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 884; Journal Issue: 1; Conference: 6. Latin American symposium on nuclear physics and applications, Iguazu (Argentina), 3-7 Oct 2005; Other Information: DOI: 10.1063/1.2710580; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; ARGON 36; ARGON 40; ASYMMETRY; BREMSSTRAHLUNG; COMPOUND NUCLEI; DIPOLES; EVAPORATION MODEL; EXCITATION; GIANT RESONANCE; HEAVY ION FUSION REACTIONS; MEV RANGE; MOLYBDENUM 100 TARGET; MOLYBDENUM 96 TARGET; PHOTON EMISSION; PROMPT GAMMA RADIATION; SPIN; SULFUR 32 REACTIONS; SULFUR 36 REACTIONS; ZIRCONIUM 92; ZIRCONIUM 96

Citation Formats

Pierroutsakou, D., Boiano, A., Di Pietro, M., Romoli, M., Martin, B., Inglima, G., De Rosa, A., La Commara, M., Sandoli, M., Dip. di Scienze Fisiche, Univ. di Napoli 'Federico II', Naples, Agodi, C., Alba, R., Colonna, M., Coniglione, R., Del Zoppo, A., Di Toro, M., Maiolino, C., Pellegriti, N., Piatelli, P., Santonocito, D., Sapienza, P., and INFN, Laboratori Nazionali del Sud, Catania. Prompt dipole {gamma}-ray emission: a new cooling mechanism in fusion heavy-ion reactions. United States: N. p., 2007. Web. doi:10.1063/1.2710580.
Pierroutsakou, D., Boiano, A., Di Pietro, M., Romoli, M., Martin, B., Inglima, G., De Rosa, A., La Commara, M., Sandoli, M., Dip. di Scienze Fisiche, Univ. di Napoli 'Federico II', Naples, Agodi, C., Alba, R., Colonna, M., Coniglione, R., Del Zoppo, A., Di Toro, M., Maiolino, C., Pellegriti, N., Piatelli, P., Santonocito, D., Sapienza, P., & INFN, Laboratori Nazionali del Sud, Catania. Prompt dipole {gamma}-ray emission: a new cooling mechanism in fusion heavy-ion reactions. United States. doi:10.1063/1.2710580.
Pierroutsakou, D., Boiano, A., Di Pietro, M., Romoli, M., Martin, B., Inglima, G., De Rosa, A., La Commara, M., Sandoli, M., Dip. di Scienze Fisiche, Univ. di Napoli 'Federico II', Naples, Agodi, C., Alba, R., Colonna, M., Coniglione, R., Del Zoppo, A., Di Toro, M., Maiolino, C., Pellegriti, N., Piatelli, P., Santonocito, D., Sapienza, P., and INFN, Laboratori Nazionali del Sud, Catania. Mon . "Prompt dipole {gamma}-ray emission: a new cooling mechanism in fusion heavy-ion reactions". United States. doi:10.1063/1.2710580.
@article{osti_21054815,
title = {Prompt dipole {gamma}-ray emission: a new cooling mechanism in fusion heavy-ion reactions},
author = {Pierroutsakou, D. and Boiano, A. and Di Pietro, M. and Romoli, M. and Martin, B. and Inglima, G. and De Rosa, A. and La Commara, M. and Sandoli, M. and Dip. di Scienze Fisiche, Univ. di Napoli 'Federico II', Naples and Agodi, C. and Alba, R. and Colonna, M. and Coniglione, R. and Del Zoppo, A. and Di Toro, M. and Maiolino, C. and Pellegriti, N. and Piatelli, P. and Santonocito, D. and Sapienza, P. and INFN, Laboratori Nazionali del Sud, Catania},
abstractNote = {We investigated the prompt dipole {gamma}-ray emission, related with entrance channel charge asymmetry effects, in the 40Ar + 92Zr and 36Ar + 96Zr fusion-evaporation reactions at Elab= 15.1 and 16 MeV/nucleon, respectively, with the aim to probe its evolution with incident energy. These reactions populate, through entrance channels having different charge asymmetries, the same compound nucleus at an average excitation energy of 304 MeV with identical spin distribution. It was shown that the dipole {gamma}-ray intensity in the bremsstrahlung subtracted linearized spectra increases by {approx}14% for the more charge asymmetric system. This result, associated with those reported for the 32,36S + 100,96Mo reaction pair at lower beam energies, implies a ''rise and fall'' trend of the prompt dipole {gamma}-ray emission with beam energy with a maximum value at Elab= 9 MeV/nucleon.},
doi = {10.1063/1.2710580},
journal = {AIP Conference Proceedings},
number = 1,
volume = 884,
place = {United States},
year = {Mon Feb 12 00:00:00 EST 2007},
month = {Mon Feb 12 00:00:00 EST 2007}
}
  • We investigated the prompt dipole {gamma}-ray emission, related with entrance channel charge asymmetry effects, in the 40Ar + 92Zr and 36Ar + 96Zr fusion reactions at Elab= 15 and 16 MeV/nucleon, respectively, with the aim to probe its evolution with incident energy. These reactions populate, through entrance channels having different charge asymmetries, the 132Ce compound nucleus at an average excitation energy of 304 MeV with identical spin distribution. Fusionlike events were selected by detecting high-energy {gamma}-rays in coincidence with evaporation residues. By studying the differential {gamma}-ray multiplicity spectra of the considered reactions, it was shown that the dipole {gamma}-ray intensitymore » increases by {approx}14% for the more charge asymmetric system. This result, associated with those reported for the 32,36S + 100,96Mo reaction pair at lower beam energies, implies a 'rise and fall' trend of the prompt dipole {gamma}-ray emission in the studied beam energy range with a maximum value at 9 MeV/nucleon.« less
  • We investigated the prompt dipole {gamma}-ray emission, related with entrance channel charge asymmetry effects, in the {sup 32}S+{sup 100}Mo and {sup 36}S+{sup 96}Mo fusion reactions at E{sub lab}=196 MeV and 214.2 MeV, respectively, with the aim to probe its evolution with incident energy. These reactions populate, through entrance channels having different charge asymmetries, the {sup 132}Ce compound nucleus at an excitation energy of 117 MeV with identical spin distribution. Fusion events were selected by detecting high-energy {gamma} rays in coincidence with evaporation residues. The center-of-mass differential {gamma}-ray multiplicity spectra of the considered reactions were found to be identical within themore » experimental uncertainties in the whole energy range. This result, associated with that reported for the same reaction pair at higher beam energy where a larger giant dipole resonance yield was evidenced for the more charge asymmetric system, implies an increasing trend of the prompt dipole {gamma}-ray emission with incident energy. Calculations based on a collective bremsstrahlung analysis of the reaction dynamics are presented and compared with the experimental findings.« less
  • The prompt {gamma}-ray emission related with the dynamical dipole mode decay was investigated in the {sup 192}Pb mass region by means of the {sup 40}Ca+{sup 152}Sm and {sup 48}Ca+{sup 144}Sm fusion-evaporation and fission reactions at E{sub lab} = 11 and 10.1 MeV/nucleon, respectively. The two reactions populate, through entrance channel having different charge asymmetries, the {sup 192}Pb compound nucleus at an excitation energy of 236 MeV with identical spin distribution. Preliminary results of this experiment show that the dynamical dipole mode survives in collisions involving heavier mass reaction partners than those studied previously. As a fast cooling mechanism on themore » fusion path, the prompt dipole {gamma} radiation could be of interest for the synthesis of super-heavy elements through ''hot'' fusion reactions.« less
  • The competition between pn and d evaporation leading to production of the same residual nucleus has been calculated in the framework of the Hauser-Feshbach theory for nine heavy-ion-induced nuclear reactions, each at several bombarding energies, for target-projectile combinations resulting in compound nuclei 12less than or equal toAless than or equal to40. The observed very good agreement between the experimental and the statistically predicted relative cross sections for pn and d emission indicates that both these exit channels proceed via evaporation from a compound nucleus.
  • From the energy spectra of light particles produced in light-heavy-ion-induced reactions, level densities of the final nuclei as well as the critical angular momenta for fusion may be obtained. The /sup 14/N, /sup 16,18/O+ /sup 12/C reactions were investigated in the energy range 30 MeV