La structure nucléaire en couches sphériques évolue en allant vers des régions de plus en plus exotiques de la carte des noyaux. Par conséquent, les nombres magiques conventionnels (2, 8, 20, 28, 50, 82, 126) peuvent disparaître loin de la stabilité, tandis que de nouveaux apparaissent.L’évolution des gaps entre états de particule individuelle loin de la stabilité a essentiellement deux origines : les dérives monopolaires et l’augmentation de la collectivité. Les dérives monopolaires sont essentiellement dues à l’interaction proton-neutron (composante spin-isospin de l’interaction nucléaire). On se concentre dans cette thèse sur les isotopes impairs N=51 et en particulier sur 83Ge, le plus proche de 79Ni que l’on peut étudier actuellement par spectroscopie γ de précision. Pour cela, deux expériences complémentaires ont été réalisées. Une première expérience, au GANIL avec AGATA, VAMOS et le plunger OUPS a permis de mesurer les durées de vie des états excités Yrast des produits de la réaction 238U(9Be,f). Une seconde expérience pour l’étude par spectroscopie γ β-retardée de 83Ge afin de peupler les états non-Yrast a été réalisée afin d’avoir une vue d’ensemble de la spectroscopie de 83Ge.La complémentarité de ces deux expériences a permis de mettre en évidence un état intru pour la première fois au delà du gap N=50 dans 83Ge et ainsi avoir plus d’information sur l’évolution du gap νg9/2νd5/2 associé au nombre magique de spin-orbite N=50. Une analyse détaillée de ses deux expériences est présentée dans ce manuscript. De plus, une comparaison avec un modèle semi-microscopique coeur-particule est aussi réalisée. / Nuclear spherical shell structure evolves towards more and more exotic regions of the nuclear chart. Therefore, conventional magic numbers (2, 8, 20, 28, 50, 82, 126) can disappear while new ones appear. 
The evolution of gaps between single-particle states far from stability has essentially two origins : monopole drift and the collectivity enhancement. The monopole drifts are mostly coming from neutron-proton interaction (spin-isospin term of the nuclear interaction). In this thesis, we focused on the study of N=51 isotones and in particular 83Ge, the closest to 79Ni that can be studied nowadays by detailled γ-spectroscopy. For this purpose, two complementary experiments were performed. A first experiment, at GANIL with AGATA, VAMOS and the OUPS plunger device allowed us to measure lifetime of Yrast excited states in the 238U(9Be,f) reaction products. A second experiment for the study of β-delayed γ-spectroscopy of 83Ge was performed in order to populate non-Yrast states so that has an overview of the spectroscopy of 83Ge.The complementarity of these two experiments allowed highlighting for the first time an intruder state above the N=50 gap in 83Ge and thus, it adds information about the evolution of the νg9/2νd5/2 gap corresponding to the N=50 shell closure.A detailed analysis of both experiments is presented in this manuscript. In addition, a comparison to a semi-microscopic core-particle model is performed.

<p> The light even-even nuclei have been studied using the den~ity dependent effective interaction of Sprung and Banerjeee The nuclei were studied initially, using a harmonic variational procedure, to deter mine the most appropriate parameters of t he force for the Hartree Fock study. </p> <p> This chosen force was then used in a comparative study of spherical nuclei to d e termine the inadequacies of our Hartn~e Fock approach, as opposed to the spherical basis calculations of Campi. Some deformed nuclei were then examined and our results were compared with those of K. Lassey and A. B. Volkov , and of J. Zofka and G. Ripka. </p> / Thesis / Master of Science (MSc)

No description available.

Com o objetivo de ampliar o conhecimento da estrutura dos núcleos duplamente ímpares da região de massa A = 130- 140, foram medidos os estados de spin elevado do ANTIPOT. 138 Pr, que se aproxima da camada fechada N = 82, através de técnicas de espectroscopia y em linha utilizando a reação ANTPOT. 128 Te (ANTIPOT. 14 N,4ny). Pela primeira vez, três bandas rotacionais foram observadas neste núcleo. Uma análise teórica da sistemática desta região foi feita com base nos modelos de \"Cranking Shell Model\" e \"Projected Shell Model\". De um modo geral, uma boa concordância foi obtida entre os resultados experimentais e teóricos. O primeiro modelo indica a coexistência de formas no ANTIPOT. 138 Pr (N=79}, enquanto o segundo sugere forma unicamente oblata. Por outro lado, os dois modelos prevêm uma transição de forma de prolato (N = 73) para oblato (N = 79) passando por uma região de triaxialidade em torno de N = 77. / With the view of extending the systematics of the odd-odd, A = 130 - 140 mass region nuclei towards the N =82 closed shell, high spin states in 138Pr nucleus have been investigated with the 128 Te(l4N,4n7) reaction, using on-line 7-ray spectroscopy techniques. For the first time three rotational bands were observed in this nucleus. A theoretical analysis of the mass region A = 130 - 140 was carried out with the Cranking Shell Model and the Projected Shell Model. Generally speaking, a good agreement was obtained between the experimental and the theoretical results. The first model indicates a shape coexistence in the 138 Pr (N =79) nucleus, while the second one shows an oblate shape. On the other hand, both models suggest a shape transition from prolate (N=73) to oblate (N=79) passing through a triaxial region around N=77.

Com o objetivo de ampliar o conhecimento da estrutura dos núcleos duplamente ímpares da região de massa A = 130- 140, foram medidos os estados de spin elevado do ANTIPOT. 138 Pr, que se aproxima da camada fechada N = 82, através de técnicas de espectroscopia y em linha utilizando a reação ANTPOT. 128 Te (ANTIPOT. 14 N,4ny). Pela primeira vez, três bandas rotacionais foram observadas neste núcleo. Uma análise teórica da sistemática desta região foi feita com base nos modelos de \"Cranking Shell Model\" e \"Projected Shell Model\". De um modo geral, uma boa concordância foi obtida entre os resultados experimentais e teóricos. O primeiro modelo indica a coexistência de formas no ANTIPOT. 138 Pr (N=79}, enquanto o segundo sugere forma unicamente oblata. Por outro lado, os dois modelos prevêm uma transição de forma de prolato (N = 73) para oblato (N = 79) passando por uma região de triaxialidade em torno de N = 77. / With the view of extending the systematics of the odd-odd, A = 130 - 140 mass region nuclei towards the N =82 closed shell, high spin states in 138Pr nucleus have been investigated with the 128 Te(l4N,4n7) reaction, using on-line 7-ray spectroscopy techniques. For the first time three rotational bands were observed in this nucleus. A theoretical analysis of the mass region A = 130 - 140 was carried out with the Cranking Shell Model and the Projected Shell Model. Generally speaking, a good agreement was obtained between the experimental and the theoretical results. The first model indicates a shape coexistence in the 138 Pr (N =79) nucleus, while the second one shows an oblate shape. On the other hand, both models suggest a shape transition from prolate (N=73) to oblate (N=79) passing through a triaxial region around N=77.

Under current investigation is the re-implementation of the Distorted-Wave Impulse Approximation (DWIA), originally formulated in FORTRAN by N.S. Chant and P.G. Roos, with the intention of developing it in a portable Python environment. This will be complimented by developing a GEANT4 detector simulation application. These two techniques will be used to model the (p,2p) proton knock-out reaction 40Ca(p; 2p)39K (2.52 MeV)1 2 + first excited state, at intermediate incident energies of 150 MeV. This study is a test-bed that lays the foundation and platform from which one may develop an interactive workbench and toolkit in GEANT4 which: (i.) accurately models an accelerator-detector experimental set-up, such as those found at iThemba Labs, and (ii.) incorporates the DWIA formalism as a built-in physics process within the framework of GEANT4. Furthermore the Python modules developed for the specific proton knock-out reaction studied here, can be generalized for an arbitrary set of nuclear scattering reactions and packaged as a suite of scientific Python codes. / Theoretical and Computational Nuclear Physics / M. Sc. (Theoretical and Computational Nuclear Physics)

Under current investigation is the re-implementation of the Distorted-Wave Impulse Approximation (DWIA), originally formulated in FORTRAN by N.S. Chant and P.G. Roos, with the intention of developing it in a portable Python environment. This will be complimented by developing a GEANT4 detector simulation application. These two techniques will be used to model the (p,2p) proton knock-out reaction 40Ca(p; 2p)39K (2.52 MeV)1 2 + first excited state, at intermediate incident energies of 150 MeV. This study is a test-bed that lays the foundation and platform from which one may develop an interactive workbench and toolkit in GEANT4 which: (i.) accurately models an accelerator-detector experimental set-up, such as those found at iThemba Labs, and (ii.) incorporates the DWIA formalism as a built-in physics process within the framework of GEANT4. Furthermore the Python modules developed for the specific proton knock-out reaction studied here, can be generalized for an arbitrary set of nuclear scattering reactions and packaged as a suite of scientific Python codes. / Theoretical and Computational Nuclear Physics / M. Sc. (Theoretical and Computational Nuclear Physics)

Le détecteur MINOS a été développé jusqu'à mi-2013 pour la spectroscopie γ prompte de noyaux très exotiques à partir de réactions d’arrachage de protons. Il est composé d'une cible épaisse d'hydrogène liquide pour augmenter la luminosité et d’une chambre à projection temporelle (TPC) pour reconstruire la position du vertex de réaction et de compenser l'effet de la cible épaisse sur la correction Doppler.La chambre à projection temporelle a été développée avec l'expertise du CEA-Irfu sur les détecteurs gazeux de type Micromegas. Dans un premier temps, différentes solutions pour la TPC ont été testées dans une chambre d'essai avec une source α et des mesures de rayons cosmiques. Des muons cosmiques ont été détectés pour la première fois en utilisant la chambre d'essai en début 2013 et ont validé l'utilisation d'un plan de détection Micromegas. Le premier prototype de TPC a été achevé en mai 2013 et nous avons utilisé un banc de rayons cosmiques pour estimer l’efficacité de la TPC.MINOS a ensuite été expédié au Japon et un test de performance sous faisceau a été réalisée à l'installation médicale HIMAC (Chiba, Japon) avec deux cibles minces au lieu de la cible épaisse d'hydrogène pour valider l'algorithme de reconstruction et la résolution de la position du vertex. Un algorithme de reconstruction de traces basé sur la transformée de Hough a été mis au point pour l'analyse des données, testé avec ces données, et comparé à des simulations.La première campagne de physique avec MINOS a eu lieu en mai 2014, avec SEASTAR. Elle s’est concentrée sur la première spectroscopie des ⁶ ⁶ Cr, ⁷⁰,⁷²Fe et ⁷⁸Ni. L'analyse de la spectroscopie du ⁶ ⁶Cr a révélé deux transitions, assignées aux deux premiers états excités. Une interprétation avec des calculs de modèle en couches montre que le maximum de collectivité quadripolaire se produit à N = 40 le long de la chaîne isotopique de chrome.Le ⁶ ⁶Cr est toujours placé dans la région de l’Îlot d’Inversion à N = 40 et les calculs de modèle en couches ainsi que la comparaison avec des calculs basés sur HFB suggèrent une extension de cet Îlot d’Inversion vers N = 50 en dessous du ⁷⁸Ni. L'analyse des ⁷⁰,⁷²Fe effectuée par C. Louchart (TU Darmstadt, Allemagne) révèle la même tendance que pour les isotopes de chrome. Les données et notre interprétation par le modèle en couches suggère une grande collectivité les Cr et Fe riches en neutrons, éventuellement jusqu'à N = 50, ce qui remettrait en cause la solidité de la fermeture de couche N = 50 en dessous du ⁷⁸Ni. / The MINOS device has been developed until mid-2013 for in-beam γ spectroscopy of very exotic nuclei from proton knockout reactions. It is composed of a thick liquid hydrogen target to achieve higher luminosities and a Time Projection Chamber (TPC) to reconstruct the vertex position and compensate for the thick target effect on the Doppler correction.The Time Projection Chamber has been developed with the expertise of CEA-IRFU in gas detectors and Micromegas detectors. At first, different solutions for the TPC were tested in a test chamber with an α source and cosmic-ray measurements. Cosmic rays were detected for the first time using the test chamber in early 2013 and validated the use of a Micromegas detection plane. The first TPC prototype was finished in May 2013, and we used a cosmic-ray bench to estimate the effiiciency of the TPC. The MINOS device was then shipped to Japan and an in-beam performance test was performed at the HIMAC medical facility (Chiba, Japan) with two thin targets instead of the thick hydrogen target to validate the tracking algorithm and the vertex position resolution. A tracking algorithm for the offline analysis based on the Hough transform has been developed, tested with the data, and compared with simulations.The first physics campaign using MINOS took place in May 2014 with SEASTAR. It focused on the first spectroscopy of ⁶ ⁶ Cr, ⁷⁰,⁷²Fe, and ⁷⁸Ni. The analysis of the ⁶⁶Cr spectroscopy revealed two transitions, assigned to the two first excited states. An interpretation with shell model calculations shows that the maximum of quadrupole collectivity occurs at N=40 along the Cr isotopic chain.⁶⁶Cr is still placed in the Island of Inversion region of N=40 and the shell model calculations as well as comparison with HFB-based calculations suggest an extension of this Island of Inversion towards N=50 below ⁷⁸Ni. The analysis of ⁷⁰,⁷²Fe performed by C. Louchart (TU Darmstadt, Germany) reveals the same trend as for Cr isotopes, with a maximum of deformation at N=42. The full data set and our shell-model interpretation suggests a large collectivity for neutron-rich Cr and Fe, possibly up to N=50, questioning the robustness of the N=50 shell closure below ⁷⁸Ni.

GPS 單點定位或稱絕對定位，傳統上使用虛擬距離觀測量，容易受到 電離層延遲影響，導致定位精度較差。因此，本文的目的為構建即時的區 域性電離層模型，以便能夠即時減弱電離層延遲量，提高單頻GPS 單點定 位的精度。 構建電離層模型的方法有很多種，而運用類神經網路為可能方法之一， 但是， 國內較少人探討。本研究嘗詴使用倒傳遞類神經網路(Back-propagation Artificial Neural Network)，構建即時的區域電離層模型，藉由選擇適當的神經訓練函數及隱藏層神經元，利用過去收集的已知參考站的雙頻GPS 資料，計算電離層延遲量，訓練類神經網路，直到精度合乎要求；再以檢核站GPS 資料，檢驗類神經網路預測電離層延遲的功效。 採用的實驗資料為臺南市政府e-GPS 系統所提供六個測站，2008 年1 月3 日到1 月5 日的GPS 資料，計算測站與GPS 衛星連線中假想的電離層 薄殼交點—電離層穿透點(Ionosphere Pierce Point, IPP）之地理位置(緯度φ、經度λ)，及太陽黑子數(sunspot numbers)等當作輸入值，IPP 的垂直電離層延遲當作輸出值，測詴包含單日、兩日以及不同的資料型態(IPP 點、網格點)等情況訓練類神經網路，藉由相對應的驗證資料，檢驗類神經網路的功效，最後將類神經網路的預估成果與全球電離層改正模型、雙頻GPS 資料計算的電離層延遲相比較，並根據改正率與統計特性，評估類神經網 路構建出的區域性電離層模型的成效。 由實驗成果顯示，構建的即時區域性電離層模型的標準差可小於±3TECU，並可改正約80%的電離層延遲誤差，故以類神經網路可有效的構 建出區域性的電離層模型。 / The conventional single point positioning using GPS pseudo rangemeasurements, are vulnerable to ionospheric errors, leading to poor positioningaccuracy. Constructing a real-time ionospheric model is one of the methods that can reduce the ionospheric errors and improve the single point positioning accuracy. Although there are many methods to construct regional ionosphere model,using artificial neural network (ANN) to construct a real-time ionospheric model is less to be mentioned. This study used back-propagation artificial neural network to estimate a regional real-time ionospheric model by selecting the appropriate training functions and the number of hidden layers and its’ nodes. The neural network had to be ‘trained’ by the computed TECs from reference stations’ duel-frequency GPS data until the required accuracy was achieved. The experimental data are collected from 6 e-GPS stations of Tainan city government on January 3 to January 5, 2008. The input values for the ANN includ the geographical location of the ionosphere pierce point (IPP) and solar activity (sunspot number). The output value are those IPPs’ vertical total electron content (VTEC). Different times range and data types (IPPs’ or raster data) for the impact of the ANN are tested. And then compared to Klobuchar model and global ionopheric model, according to the correct rate and the ΔTEC statistic table decide the effectiveness of ANN. According to the test results, the regional ionopheric model constructed by ANN can corrected 80% of the ionospheric errors, the standard deviation of ΔTEC is less than ±3TECU.

Nous présentons une approche alternative aux diagonalisations exactes de calculs en modèles en couches pour l'étude microscopique de la structure nucléaire. Nous avons tout d'abord minimisé l'énergie totale du système par la résolution des équations Hartree-Fock dans la base définie par l'espace de valence du modèle en couches. Nous avons finalisé la mise au point de ce programme par comparaison des résultats avec les solutions de problèmes solubles analytiquement comme ceux d'un hamiltonien SU(3) ou par comparaison avec des diagonalisations exactes du modèle en couches. Ensuite, nous avons mis au point des procédures pour l'obtention de ces mêmes calculs avec contraintes pour une description complète de la surface d'énergie potentielle d'un noyau donné en fonction des degrés de liberté Q20 et Q22. La restauration du moment angulaire par méthode de projections a permis d'obtenir les spectres des noyaux rotationnels dans le cas axial et dans le cas triaxial. Enfin, la méthode des coordonnées génératrices a permis le mélange de ces déterminants de Slater non orthogonaux. Parmi les différentes applications, nous avons pu décrire les noyaux déformés le long de la ligne N=Z autour du80Zr ou un nouvel îlot d'inversion à N=50. / We present an alternative approach to shell diagonalizations for microscopic description of nuclear structure. First we minimized the total system energy solving the Hartree-Fock equations within the shell model valence space. The results are compared with exact shell model diagonalization and an exact soluble SU(3) hamiltonian. Then, we developed procedures to obtain the same of type calculations with constrained conditions on the quadrupole degrees of freedom to obtain the full potential energy surfaces. The angular momentum restauration was obtained through projection method to generate rotionnal spectra of nuclei in both axial and triaxial cases. Finally the generate coordinate method was applied to mix several of these non-orthogonal Slater determinants. Among several applications we managed to describe deformed nuclei along the N=Z line around 80Zr or a new island of deformation at N=50. Finally, a first application in the superheavy region predicts a spherical gap for the Z=114, N=184 isotope