Low-Background In-Trap Decay Spectroscopy with TITAN at TRIUMF

An in-trap decay spectroscopy setup has been developed and constructed for use with the TITAN facility at TRIUMF. The goal of this device is to observe weak electron-capture (EC) branching ratios for the odd-odd intermediate nuclei in the $\beta\beta$ decay process. This apparatus consists of an up-to 6 Tesla, open-access spectroscopy ion-trap, surrounded radially by up to 7 planar Si(Li) detectors which are separated from the trap by thin Be windows. This configuration provides a significant increase in sensitivity for the detection of low-energy photons by providing backing-free ion storage and eliminating charged-particle-induced backgrounds. An intense electron beam is also employed to increase the charge-states of the trapped ions, thus providing storage times on the order of minutes, allowing for decay-spectroscopy measurements. The technique of multiple ion-bunch stacking was also recently demonstrated, which further extends the measurement possibilities of this apparatus. The current status of the facility and initial results from a $^{116}$In measurement are presented.Comment: Proceedings for the 2nd International Conference on Advances in Radioactive Isotope Science (ARIS2014

Precision mass measurements of magnesium isotopes and implications on the validity of the Isobaric Mass Multiplet Equation

If the mass excess of neutron-deficient nuclei and their neutron-rich mirror partners are both known, it can be shown that deviations of the Isobaric Mass Multiplet Equation (IMME) in the form of a cubic term can be probed. Such a cubic term was probed by using the atomic mass of neutron-rich magnesium isotopes measured using the TITAN Penning trap and the recently measured proton-separation energies of $^{29}$Cl and $^{30}$Ar. The atomic mass of $^{27}$Mg was found to be within 1.6$\sigma$ of the value stated in the Atomic Mass Evaluation. The atomic masses of $^{28,29}$Mg were measured to be both within 1$\sigma$, while being 8 and 34 times more precise, respectively. Using the $^{29}$Mg mass excess and previous measurements of $^{29}$Cl we uncovered a cubic coefficient of $d$ = 28(7) keV, which is the largest known cubic coefficient of the IMME. This departure, however, could also be caused by experimental data with unknown systematic errors. Hence there is a need to confirm the mass excess of $^{28}$S and the one-neutron separation energy of $^{29}$Cl, which have both come from a single measurement. Finally, our results were compared to ab initio calculations from the valence-space in-medium similarity renormalization group, resulting in a good agreement.Comment: 7 pages, 3 figure

Triangle-Free Penny Graphs: Degeneracy, Choosability, and Edge Count

We show that triangle-free penny graphs have degeneracy at most two, list coloring number (choosability) at most three, diameter $D=\Omega(\sqrt n)$, and at most $\min\bigl(2n-\Omega(\sqrt n),2n-D-2\bigr)$ edges.Comment: 10 pages, 2 figures. To appear at the 25th International Symposium on Graph Drawing and Network Visualization (GD 2017

Breakdown of the Isobaric Multiplet Mass Equation for the A = 20 and 21 Multiplets

Using the Penning trap mass spectrometer TITAN, we performed the first direct mass measurements of 20,21Mg, isotopes that are the most proton-rich members of the A = 20 and A = 21 isospin multiplets. These measurements were possible through the use of a unique ion-guide laser ion source, a development that suppressed isobaric contamination by six orders of magnitude. Compared to the latest atomic mass evaluation, we find that the mass of 21Mg is in good agreement but that the mass of 20Mg deviates by 3{\sigma}. These measurements reduce the uncertainties in the masses of 20,21Mg by 15 and 22 times, respectively, resulting in a significant departure from the expected behavior of the isobaric multiplet mass equation in both the A = 20 and A = 21 multiplets. This presents a challenge to shell model calculations using either the isospin non-conserving USDA/B Hamiltonians or isospin non-conserving interactions based on chiral two- and three-nucleon forces.Comment: 5 pages, 2 figure

Anthropogenic Space Weather

Anthropogenic effects on the space environment started in the late 19th century and reached their peak in the 1960s when high-altitude nuclear explosions were carried out by the USA and the Soviet Union. These explosions created artificial radiation belts near Earth that resulted in major damages to several satellites. Another, unexpected impact of the high-altitude nuclear tests was the electromagnetic pulse (EMP) that can have devastating effects over a large geographic area (as large as the continental United States). Other anthropogenic impacts on the space environment include chemical release ex- periments, high-frequency wave heating of the ionosphere and the interaction of VLF waves with the radiation belts. This paper reviews the fundamental physical process behind these phenomena and discusses the observations of their impacts.Comment: 71 pages, 35 figure

A novel transparent charged particle detector for the CPET upgrade at TITAN

The detection of an electron bunch exiting a strong magnetic field can prove challenging due to the small mass of the electron. If placed too far from a solenoid's entrance, a detector outside the magnetic field will be too small to reliably intersect with the exiting electron beam because the light electrons will follow the diverging magnetic field outside the solenoid. The TITAN group at TRIUMF in Vancouver, Canada, has made use of advances in the practice and precision of photochemical machining (PCM) to create a new kind of charge collecting detector called the "mesh detector." The TITAN mesh detector was used to solve the problem of trapped electron detection in the new Cooler PEnning Trap (CPET) currently under development at TITAN. This thin array of wires etched out of a copper plate is a novel, low profile, charge agnostic detector that can be made effectively transparent or opaque at the user's discretion.Comment: 6 Pages. 6 Figures. Submitted to Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipmen