Magnetic Lens Spectrometer Investigation of Gamma-Radiation from Light Nuclei

Author: Mackin, Robert James

Year: 1953

Degree: Dissertation (Ph.D.)

Advisor: Lauritsen, Thomas

Committee Member: Unknown, Unknown

Option: Physics; Mathematics

DOI: 10.7907/VZNC-P757

Abstract

A magnetic lens spectrometer has been used in conjunction with an electrostatic accelerator to study gamma-radiation produced by light-nuclear reactions. The apparatus and techniques for its use are described. Formulas are given which are used in analyzing the data.

A radiative transition in Li6, produced by the (resonant) reaction Be[superscript 9](p, a)Li6* was studied in detail. The gamma-ray energy was found to be 3.572± 0.012 Mev, not correcting for a 0.026-Mev Doppler shift. The internal pair spectrum was strong evidence that the transition proceeded by magnetic dipole (M1) radiation, but electric quadrupole (E2) was not finally excluded. Capture radiation from the same resonance has energy 8.1 ± 0.2 Mev and is 103 times less intense.

The internal pair spectrum from the first excited state of Be10 (produced by Be9(dp)Be10*) showed the radiation to be E2. The internal pairs from the 3.60-Mev transition of B10 exclude El for that radiation. Gamma-rays assigned to B10 were measured (without Doppler correction) as 3.595 ± 0.014, 4.44 ± 0.03, and 5.98 ± 0.04 Mev. The last named was assigned to the 5.93-Mev level of B10.

Gamma-rays produced by C12 + D2 have energies 3.843 ± 0.014, 3.684 ± 0.020, and 0.1682 ± 0.001 Mev. On the basis of data presented, the first two are assigned to levels of those energies in C13 and the last as a transition between them. Arguments are given that the presence of this low-energy transition, in conjunction with other data, assigns spins 5/2, even, and 3/2, odd, to the respective levels. The internal pairs agree with M2 for the higher-energy radiation but definitely exclude only El. Internal pair data for the 3.68-Mev transition is inconclusive, but suggests E2 or E1.

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