Gamma decay of virtual states in ²⁰Ne and ¹⁶O excited in radiative alpha-particle capture
<p>A cryogenically pumped, windowless gas target has been used to study the radiative alpha-capture reaction on <sup>16</sup>O and <sup>12</sup>C targets, giving information on the electromagnetic decay properties of various unbound states in <sup>20</sup>N...
| Главные авторы: | , |
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| Другие авторы: | |
| Формат: | Диссертация |
| Язык: | English |
| Опубликовано: |
1980
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| _version_ | 1826305371743977472 |
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| author | Hurst, M Hurst, Michael John |
| author2 | Allen, K |
| author_facet | Allen, K Hurst, M Hurst, Michael John |
| author_sort | Hurst, M |
| collection | OXFORD |
| description | <p>A cryogenically pumped, windowless gas target has been used to study the radiative alpha-capture reaction on <sup>16</sup>O and <sup>12</sup>C targets, giving information on the electromagnetic decay properties of various unbound states in <sup>20</sup>Ne and <sup>16</sup>O. Several states in <sup>20</sup>Ne have been observed in this reaction for the first time.</p> <p>The first five unit-isospin, natural parity states in <sup>20</sup>Ne have been observed. The isospin assignment of the 11.27 MeV (1<sup>-</sup>)) state has been made definite by the observation of a strong Ml decay to the 8.85 MeV (1<sup>-</sup>)state, and the analogue of the 1.97 MeV state in <sup>20</sup>F has been identified with the <sup>20</sup>Ne state at 12.25 MeV. Angular distribution measurements have shown the spin of this state to be 3<sup>-</sup>), and the total width has been shown to be less than 1 keV, contradicting previous reports. The 12.22 MeV (2<sup>+</sup>)state has been resolved clearly as an individual resonance for the first time. The electromagnetic transition rates for the lower T=l states in <sup>20</sup>Ne are compared with shell model calculations.</p> <p>Five zero-isospin capture resonances in <sup>20</sup>Ne have been studied, the gamma-decay of the 8.70 MeV (1<sup>-</sup>), 9.11 MeV (3<sup>-</sup>) and 11.92 MeV (4<sup>+</sup>) states being observed for the first time. A remeasurement has been made of the enhanced E2 decay strength of the 8<sup>+</sup> member of the ground state rotational band, giving <sup>ω</sup>=l31 <sup>±</sup>18 meV, in agreement with a previous less accurate value. This result is compared with shell model calculations.</p> <p>A study of the capture reaction on <sup>12</sup>C has been performed in the beam energy range 5.22 MeV < Eα < 9.53 MeV. No new capture resonances have been found but the known inelastic resonances have been seen. The 11.10 MeV (4<sup>+</sup>) state has been studied and the strength for the decay to the 6.13 MeV (3<sup>-</sup>) state has been shown to be only half of a previous result. The 12.05 MeV (0<sup>+</sup>) state has not been observed, but a limit has been placed on its strength.</p> |
| first_indexed | 2024-03-07T06:31:53Z |
| format | Thesis |
| id | oxford-uuid:f643792e-98ec-44d5-ad8e-c6d8ab1801db |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-03-07T06:31:53Z |
| publishDate | 1980 |
| record_format | dspace |
| spelling | oxford-uuid:f643792e-98ec-44d5-ad8e-c6d8ab1801db2022-03-27T12:33:48ZGamma decay of virtual states in ²⁰Ne and ¹⁶O excited in radiative alpha-particle captureThesishttp://purl.org/coar/resource_type/c_db06uuid:f643792e-98ec-44d5-ad8e-c6d8ab1801dbNuclear structureEnglishPolonsky Theses Digitisation Project1980Hurst, MHurst, Michael JohnAllen, KAllen, K<p>A cryogenically pumped, windowless gas target has been used to study the radiative alpha-capture reaction on <sup>16</sup>O and <sup>12</sup>C targets, giving information on the electromagnetic decay properties of various unbound states in <sup>20</sup>Ne and <sup>16</sup>O. Several states in <sup>20</sup>Ne have been observed in this reaction for the first time.</p> <p>The first five unit-isospin, natural parity states in <sup>20</sup>Ne have been observed. The isospin assignment of the 11.27 MeV (1<sup>-</sup>)) state has been made definite by the observation of a strong Ml decay to the 8.85 MeV (1<sup>-</sup>)state, and the analogue of the 1.97 MeV state in <sup>20</sup>F has been identified with the <sup>20</sup>Ne state at 12.25 MeV. Angular distribution measurements have shown the spin of this state to be 3<sup>-</sup>), and the total width has been shown to be less than 1 keV, contradicting previous reports. The 12.22 MeV (2<sup>+</sup>)state has been resolved clearly as an individual resonance for the first time. The electromagnetic transition rates for the lower T=l states in <sup>20</sup>Ne are compared with shell model calculations.</p> <p>Five zero-isospin capture resonances in <sup>20</sup>Ne have been studied, the gamma-decay of the 8.70 MeV (1<sup>-</sup>), 9.11 MeV (3<sup>-</sup>) and 11.92 MeV (4<sup>+</sup>) states being observed for the first time. A remeasurement has been made of the enhanced E2 decay strength of the 8<sup>+</sup> member of the ground state rotational band, giving <sup>ω</sup>=l31 <sup>±</sup>18 meV, in agreement with a previous less accurate value. This result is compared with shell model calculations.</p> <p>A study of the capture reaction on <sup>12</sup>C has been performed in the beam energy range 5.22 MeV < Eα < 9.53 MeV. No new capture resonances have been found but the known inelastic resonances have been seen. The 11.10 MeV (4<sup>+</sup>) state has been studied and the strength for the decay to the 6.13 MeV (3<sup>-</sup>) state has been shown to be only half of a previous result. The 12.05 MeV (0<sup>+</sup>) state has not been observed, but a limit has been placed on its strength.</p> |
| spellingShingle | Nuclear structure Hurst, M Hurst, Michael John Gamma decay of virtual states in ²⁰Ne and ¹⁶O excited in radiative alpha-particle capture |
| title | Gamma decay of virtual states in ²⁰Ne and ¹⁶O excited in radiative alpha-particle capture |
| title_full | Gamma decay of virtual states in ²⁰Ne and ¹⁶O excited in radiative alpha-particle capture |
| title_fullStr | Gamma decay of virtual states in ²⁰Ne and ¹⁶O excited in radiative alpha-particle capture |
| title_full_unstemmed | Gamma decay of virtual states in ²⁰Ne and ¹⁶O excited in radiative alpha-particle capture |
| title_short | Gamma decay of virtual states in ²⁰Ne and ¹⁶O excited in radiative alpha-particle capture |
| title_sort | gamma decay of virtual states in ²⁰ne and ¹⁶o excited in radiative alpha particle capture |
| topic | Nuclear structure |
| work_keys_str_mv | AT hurstm gammadecayofvirtualstatesin20neand16oexcitedinradiativealphaparticlecapture AT hurstmichaeljohn gammadecayofvirtualstatesin20neand16oexcitedinradiativealphaparticlecapture |