Use this URL to cite or link to this record in EThOS: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.561659
Title: Resonant two proton decay from ¹⁴O* using a radioactive beam
Author: Bain, Carlos
Awarding Body: University of Edinburgh
Current Institution: University of Edinburgh
Date of Award: 1995
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Abstract:
Two experiments were carried out to search for and identify the mechanism for two proton emission from the 7.77 MeV (Jπ = 2⁺, Γ = 76 ± 10keV) excited state in ¹⁴O. The experiments were performed at the Radioactive Ion Beams Facility at Louvain­la­Neuve, in Belgium, using a 45 MeV beam of radioactive ¹³N³⁺ ions on a [CH₂]n target to populate the state. The protons and other particles were detected using the Louvain­Edinburgh Detector Array, LEDA, a large area annular silicon strip detector. Control experiments with a ¹²C target and with a degraded beam energy were also made. Proton­proton coincidence measurements made in the commissioning run identified a two proton decay component. However, the large background (~90%) caused by evaporation protons from the fusion of ¹³N with ¹²C prevented an analysis of the decay mechanism. The follow up experiment utilised two LEDA detectors whereby the protons of interest would be stopped in the front detector with the back detector acting as a veto for high energy protons. Comparison of data with simulations for the decay mechanisms revealed the decay to be dominantly a sequential emission of two protons via the 2.37 MeV (Jπ = 1/2⁺, Γ = 33.7 ± 0.9 keV) state in ¹³N to the ground state in ¹²C. This decay mode has a measured partial width of 125 ± 20 eV which represents a 0.16% branching ratio. Theoretical predictions for this value give a width of 3 ± 1 keV which gives a spectroscopic factor of θ² = 0:04. Simulations using a model for ²He or diproton emission have resulted in an upper limit of 5% being set which corresponds to ~6 eV (95% confidence limit). Calculation for this width with a spectroscopic factor of unity give a value of 15 ± 5 eV. Hence an upper limit for the spectroscopic factor of θ² = 0:4 can be set which is above the value of 0.22 predicted by B.A. Brown.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.561659  DOI: Not available
Keywords: nuclear physics
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