Session C4: Nuclear Physics II

Progress With The Titan Mass Spectrometer

TITAN consists of several ion traps that manipulate and study exotic, short-lived nuclei. TITAN has measured the masses of the shortest-lived nuclides ever investigated, using the technique of time-of-flight ion cyclotron resonance. To support precision measurements, TITAN deploys an Electron Beam Ion Trap (EBIT), a Cooler PEnning Trap (CPET) and a Multi-Reflection Time-of-Flight mass spectrometer (MR-ToF). The latter two are being commissioned offline while the EBIT is in operation and charge-breeds ions before sending them to the precision Penning trap for mass measurements. The EBIT has demonstrated the recapture of beta-decay daughters and can be used as an ion source for elements not produced at TRIUMF's ISAC facility. Recently, the EBIT's emittance properties have been improved so transfer efficiency between the EBIT and the Penning trap has subsequently improved. CPET has demonstrated the capture and self-cooling of a plasma of 10$^{\mathrm{9}}$ electrons, and is being altered to accommodate anti-parallel beams of electrons and positively charged ions for simultaneous trapping. MR-ToF's commissioning has proceeded to the point where it can demonstrate a mass resolving power \textgreater 8E4.\\ \\In collaboration with: (TRIUMF) C. Babcock, B. Barquest, At Gallant, M. Good, J. Dilling, (MANITOBA) U. Chowdhury, B. Kootte, G. Gwinner, (UBC) A. Finaly, Y. Lan, E. Leistenschneider, (SURREY) M. Foster, (MPIK) R. Klawitter, (GSI) MP Reiter, (SFU) D. Short, C. Andreiou   

Steps Towards Implementing TITAN's Cooler Penning Trap

Masses of short-lived isotopes are essential inputs for a number of fields of physics. These include, but are not limited to, studies in astrophysics and nuclear physics. TRIUMF’s Ion Trap for Atomic and Nuclear physics (TITAN) utilizes Penning trap mass spectrometry to determine such masses. Charge breeding of the singly charged ions typically measured in such a trap shows great promise for increasing the capability of TITAN to perform high precision mass measurements of these isotopes. Mass measurements have been successfully performed on highly charged isotopes, but the maximal improvements in precision have not yet been realized due to an increase in energy spread resulting from the charge breeding process. In order to reduce this energy spread in the future prior to measurement, we are in the process of commissioning a Cooler Penning Trap (CPET). In this talk I will discuss the status of CPET in the context of the TITAN facility at TRIUMF and the steps we are taking towards its implementation.   

Gleaning the {\ss}{\ss} decay half-life of $^{\mathrm{96}}$Zr from billion year old zircons

The decay of $^{\mathrm{96}}$Zr is of notable interest as a $\beta \beta $ decay candidate. Wieser and DeLaeter determined its $\beta \beta $ decay half-life by measuring an isotopic anomaly of the $^{\mathrm{96}}$Mo daughter in ancient zircons, yielding a value of 0.94(32)x10$^{\mathrm{19}}$ a. More recently, the NEMO collaboration measured the half-life by a direct count rate measurement to be 2.4(3)x10$^{\mathrm{19\thinspace }}$a, twice as long as the geochemical measurement. We aim to study this discrepancy through a series of experiments combining nuclear physics and geochemical techniques. We are measuring the amount of daughter product of the $\beta \beta $ decay of $^{\mathrm{96}}$Zr$\to ^{\mathrm{96}}$Mo in ancient zircons with ages from 500 Ma to 2.5 Ga using modern chemical preparation techniques and instrumentation. The zirconium silicates, which have remained a closed system over their lifetimes, are especially suitable for this investigation due to their high zirconium content and the low natural molybdenum abundance. This makes it possible to detect the small amount of accumulated decay product. These measurements are being performed in conjunction with beta decay Q-value measurements at the University of Jyv\"{a}skyl\"{a} JYFLTRAP experiment, a high precision mass measurement penning trap for atomic and nuclear science. Combined, these measurements will help to resolve the discrepancy of the two independent measurements.   

Time reversal violation in radiative beta decay

Some explanations for the excess of matter over antimatter in the universe involve sources of time reversal violation (TRV) in addition to the one known in the standard model of particle physics. We plan to search for TRV in a correlation between the momenta of the beta, neutrino, and the radiative gamma sometimes emitted in nuclear beta decay. Correlations involving three momenta are sensitive at lowest order to different TRV physics than observables involving spin, such as electric dipole moments. Similar experiments have been done in radiative kaon decay, but not in systems involving the lightest generation of quarks. The explicit low-energy physics model being tested [Gardner and He, Phys. Rev. D 87 116012 (2013)] produces effects in the Fermi beta decay of the neutron, tritium, and some positron-decaying isotopes. We will try to measure the TRV asymmetry in radiative beta decay of laser-trapped $^{38m}$K at better than 0.01 sensitivity, and we will describe solutions to measure radiative gammas in the presence of background from positron annihilation.   

Neutron activation analysis via nuclear decay kinetics using gamma-ray spectroscopy

Gamma-ray spectroscopy is a powerful tool used in a variety of fields including nuclear and analytical chemistry, environmental science, and health risk management. At SFU, the Germanium detector for Elemental Analysis and Radiation Studies (GEARS), a low-background shielded high-purity germanium gamma-ray detector, has been used recently in all of the above fields. The current project aims to simultaneously expand the number of applications for which GEARS can be used while enhancing its functionality. A recent addition to the SFU Nuclear Science laboratory is the Thermo Scientific P 385 neutron generator. This device is capable of producing up to 3.65$\times$10$^8$ neutrons/s providing the capacity for neutron activation analysis, thereby opening a major avenue of research which was previously unavailable at SFU. The isotopes created via neutron activation have a wide range of half-lives. To measure activities of isotopes with short half-lives, a new analog data acquisition system has been installed on GEARS allowing accurate measurements of decay kinetics. This new functionality enables identification and quantification of unknown products of neutron activation. Results from the neutron activation analysis of pure metals and environmental samples will be presented.