Bunching, cooling, and measuring of radioactive isotopes for nuclear physics

Jeffrey Charles Bale
TRIUMF is currently undergoing a major expansion of its capabilities to produce exotic ion beams for experiments. In this thesis, I review a portion of the new infrastructure that I helped to design, the CANadian Rare-isotope facility with Electron-Beam ion source's Radio Frequency Quadrupole buncher and cooler. The portion that I was responsible for was the injection optics into this buncher and cooler. The studies found a solution to exceed the acceptance requirements of the device, 15 mm
more » ... by a factor of five, resulting in an acceptance of 67±7 mm mrad for masses of ions as low as 15 AMU, as well as 72±7 mm mrad for masses above 30 AMU. These results came about from simulating both the length of a tapered region in the injection optics, as well as the angle of the taper region with respect to the beam axis The optimal design of the tapered region was have a length of 50 mm at an angle of 4⁰. In addition to these simulations, energy spread investigations were conducted. These studies resulted in a maximum loss of 14% of the acceptance of the device when the delivered beam has an energy spread of 25%. In addition to the design of the injection optics for the buncher and cooler, mass measurements of several short-lived isotopes at Triumf's Ion Trap for Atomic and Nuclear science were analysed. All of the investigated masses have reduced uncertainties when compared to previous values in the Atomic Mass Evaluation of 2012. Mass excesses for ³¹ ³²Na were found to be 12246(14) keV and 18638(37) keV, respectively, with uncertainties being half of the smallest of those currently published in AME. Mass excess of ²⁹ ³⁴ ³⁵Al were shown to be -18207.77(37) keV, -3000.5(29) keV, and -223.7(73) keV. The mass excess of ³⁴Al has also confirmed the two-neutron separation energy cross over with ³³Mg to be 15(10) keV at a N=21. These nuclear physics studies are discussed in context of the so-called island of inversion and nuclear correlation energy.
doi:10.14288/1.0300657 fatcat:3ilzf34vqneofeg2nb3utkrrlq