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A Binding Energy Study of the Atomic Mass Evaluation 2012 and an Updated Beta-Decay Study of Neutron-Rich 74CuTracy, James L, Jr 09 December 2016 (has links)
A study of ground state binding energy values listed in the Atomic Mass Evaluation 2012 (AME2012) using an interpretive approach, as opposed to the exploratory methods of previous models, is presented. This model is based on a postulate requiring all protons to pair with available neutrons to form bound alpha clusters as the ground state for anN = Z core upon which excess neutrons are added. For each core, the trend of the binding energy as a function of excess neutrons in the isotopic chain can be fit with a three-term quadratic function. The quadratic parameter reveals a smooth decaying exponential function. By re-envisioning the determination of mass excess, the constant-term fit parameters, representing N = Z nuclei, reveal a near-symmetry around Z = 50. The linear fit parameters exhibit trends which are linear functions of core size. A neutron drip-line prediction is compared against current models. By considering the possibility of an alpha-cluster core, a new ground-state structure grouping scheme is presented; nucleon-nucleon pairing is shown to have a greater role in level filling. This model, referred to as the Alpha-Deuteron-Neutron Model, yields promising first results when considering root-mean-square variances from the AME2012. The beta-decay of the neutron-rich isotope 74Cu has been studied using three highpurity Germanium clover detectors at the Holifield Radioactive Ion Beam Facility at Oak Ridge National Laboratory. A high-resolution mass separator greatly improved the purity of the 74Cu beam by removing isobaric contaminants, thus allowing decay through its isobar chain to the stable 74Ge at the center of the LeRIBSS detector array without any decay chain member dominating. Using coincidence gating techniques, 121 gamma-rays associated with 74Cu were isolated from the collective singles spectrum. Eighty-seven of these were placed in an expanded level scheme, and updated betaeeding level intensities and log(ft) values are presented based on multiple newly-placed excited states up to 6.8 MeV. The progression of simulated Total Absorption gamma-ray Spectroscopy (TAGS) based on known levels and beta feeding values from previous measurements to this evaluation are presented and demonstrate the need for a TAGS measurement of this isotope to gain a more complete understanding of its decay scheme.
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A feasibility study of the (3He,8He) reaction with the K600 magnetic spectrometerSwartz, Jacobus Andreas 03 1900 (has links)
Thesis (MSc (Physics))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: Highly exotic nuclei can be studied in rare reactions using stable beams, with macroscopic
intensities, and thick targets. Exotic nuclei are interesting for a number of reasons e.g. for
testing nuclear models under conditions of high isospins. In the case of very neutron-deficient
nuclei, two-proton decay is the most recently discovered nuclear decay mode and the subject of
many theoretical investigations involving cluster and shell models.
This thesis presents a feasibility study of investigating light exotic nuclei near the proton drip
line with the K600 magnetic spectrometer. The 27Al(3He,8He)22Al five-neutron pick-up reaction
was investigated at a spectrometer angle of θlab = 8◦ with a beam energy of Elab = 220 MeV.
This reaction can be used to populate highly neutron-deficient nuclei. Should the study of this
reaction prove to be feasible, then a number of nuclei on the proton drip line or beyond could be
investigated. A new data acquisition system, with VME electronics and MIDAS software, was
used along with one new drift chamber, which consists of both an X wire plane and a U wire
plane. The particles 1,2,3H and 3,4He were all identified as outgoing particles from the collision of
3He with 27Al. Cross section calculations were performed for these observed reactions. Discrete
spectra for the (3He,6He) and (3He,8He) reactions could not be identified.
The mass calculation of A ∼ 20 nuclei on the proton drip line depends on the determination
of the Coulomb energy, which differs a lot between mirror nuclei. Mass calculations were performed
for known nuclei in the mass region A ≤ 50, using the Isobaric Multiplet Mass Equation.
Agreement with experimental data was found to be far better in odd nuclei than in even nuclei.
Hence mass predictions were performed for odd nuclei along the proton drip line. / AFRIKAANSE OPSOMMING: Hoogs eksotiese kerne kan bestudeer word in seldsame reaksies deur middel van stabiele bundels,
met makroskopiese intensiteite, en dik teikens. Eksotiese kerne is interessant om verskeie
redes, onder andere om kernfisiese modelle te toets onder omstandighede van ho¨e isospin. In die
geval van baie neutron-arm kerne is twee-proton verval die nuutste ontdekte tipe van kernverval.
Dit is ook die onderwerp van vele teoretiese studies met betrekking tot bondel en skilmodelle.
Hierdie tesis beskryf ‘n uitvoerbaarheidstudie vir die ondersoek van ligte eksotiese kerne naby
die proton drup lyn met behulp van die K600 magnetiese spektrometer. Die 27Al(3He,8He)22Al
vyf-neutron kaapreaksie is ondersoek by ‘n spektrometer hoek van θlab = 8◦ met ‘n bundel energie
van Elab = 220 MeV. Sou die uitvoerbaarheidstudie van hierdie reaksie slaag, dan kan verskeie
kerne op of anderkant die proton drup lyn ondersoek word. ‘n Nuwe data verkrygingssisteem, met
VME elektronika en MIDAS sagteware, is gebruik saam met een nuwe dryfkamer, wat bestaan
uit beide ‘n X draadvlak en ‘n U draadvlak. Die partikels 1,2,3H en 3,4He is almal geidentifiseer
as uitgaande partikels van die botsing van 3He met 27Al. Kansvlak-berekeninge is uitgevoer vir
alle waargenome reaksies. Diskrete spektra kon nie gevind word vir die (3He,6He) of (3He,8He)
reaksies nie.
Die massa berekening van A ∼ 20 kerne op die proton drup lyn is afhanklik van die bepaling
van die Coulomb energie, wat baie verskil tussen spie¨elkerne. Massa berekeninge is uitgevoer vir
bekende kerne in die massa gebied A ≤ 50, deur die gebruik van die Isobariese Multiplet Massa
Vergelyking. Die ooreenstemming met eksperimentele data was baie beter in die geval van onewe
kerne as met ewe kerne. Daarom was die massa voorspellings uitgevoer vir slegs onewe kerne
naby die proton drup lyn.
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