TRIUMF's Ion Trap For Atomic And Nuclear Science Research Articles

Collision-Induced Dissociation at TRIUMF's Ion Trap for Atomic and Nuclear science

The performance of high-precision mass spectrometry of radioactive isotopes can often be hindered by large amounts of contamination, including molecular species, stemming from the production of the radioactive beam. In this paper, we report on the development of Collision-Induced Dissociation (CID) as a means of background reduction for experiments at TRIUMF's Ion Trap for Atomic and Nuclear science (TITAN). This study was conducted to characterize the quality and purity of radioactive ion beams and the reduction of molecular contaminants to allow for mass measurements of radioactive isotopes to be done further from nuclear stability. This is the first demonstration of CID at an ISOL-type radioactive ion beam facility, and it is shown that molecular contamination can be reduced up to an order of magnitude.

Summit of the N=40 island of inversion: Precision mass measurements and ab initio calculations of neutron-rich chromium isotopes

Mass measurements continue to provide invaluable information for elucidating nuclear structure and scenarios of astrophysical interest. The transition region between the Z=20 and 28 proton shell closures is particularly interesting due to the onset and evolution of nuclear deformation as nuclei become more neutron-rich. This provides a critical testing ground for emerging ab-initio nuclear structure models. Here, we present high-precision mass measurements of neutron-rich chromium isotopes using the sensitive electrostatic Multiple-Reflection Time-Of-Flight Mass Spectrometer (MR-TOF-MS) at TRIUMF's Ion Trap for Atomic and Nuclear Science (TITAN) facility. Our high-precision mass measurements of 59,61−63Cr confirm previous results, and the improved precision in measurements of 64−65Cr refine the mass surface beyond N=40. With the ab initio in-medium similarity renormalization group, we examine the trends in collectivity in chromium isotopes and give a complete picture of the N=40 island of inversion from calcium to nickel.

Mass measurements of neutron-rich gallium isotopes refine production of nuclei of the first r -process abundance peak in neutron-star merger calculations

We report mass measurements of neutron-rich Ga isotopes $^{80-85}$Ga with TRIUMF's Ion Trap for Atomic and Nuclear science (TITAN). The measurements determine the masses of $^{80-83}$Ga in good agreement with previous measurements. The masses of $^{84}$Ga and $^{85}$Ga were measured for the first time. Uncertainties between $25-48$ keV were reached. The new mass values reduce the nuclear uncertainties associated with the production of A $\approx$ 84 isotopes by the \emph{r}-process for astrophysical conditions that might be consistent with a binary neutron star (BNS) merger producing a blue kilonova. Our nucleosynthesis simulations confirm that BNS merger may contribute to the first abundance peak under moderate neutron-rich conditions with electron fractions $Y_e=0.35-0.38$.

Dawning of the N=32 Shell Closure Seen through Precision Mass Measurements of Neutron-Rich Titanium Isotopes.

A precision mass investigation of the neutron-rich titanium isotopes ^{51-55}Ti was performed at TRIUMF's Ion Trap for Atomic and Nuclear science (TITAN). The range of the measurements covers the N=32 shell closure, and the overall uncertainties of the ^{52-55}Ti mass values were significantly reduced. Our results conclusively establish the existence of the weak shell effect at N=32, narrowing down the abrupt onset of this shell closure. Our data were compared with state-of-the-art abinitio shell model calculations which, despite very successfully describing where the N=32 shell gap is strong, overpredict its strength and extent in titanium and heavier isotones. These measurements also represent the first scientific results of TITAN using the newly commissioned multiple-reflection time-of-flight mass spectrometer, substantiated by independent measurements from TITAN's Penning trap mass spectrometer.

High-precision QEC -value measurement of the superallowed β+ emitter Mg22 and an ab initio evaluation of the A=22 isobaric triplet

A direct $Q_{EC}$-value measurement of the superallowed $\beta^+$ emitter $^{22}$Mg was performed using TRIUMF's Ion Trap for Atomic and Nuclear science (TITAN). The direct ground-state to ground-state atomic mass difference between $^{22}$Mg and $^{22}$Na was determined to be $Q_{EC}=4781.40(22)$~keV, representing the most precise single measurement of this quantity to date. In a continued push towards calculating superallowed isospin-symmetry-breaking (ISB) corrections from first principles, ab-initio shell-model calculations of the $A=22$ IMME are also presented for the first time using the valence-space in-medium similarity renormalization group formalism. With particular starting two- and three-nucleon forces, this approach demonstrates a level of agreement with the experimental data that suggests reliable ab-initio calculations of superallowed ISB corrections are now possible.

First direct mass measurement of the neutron-deficient nucleusAl24

The first direct mass measurement of the neutron-deficient nucleus $^{24}\mathrm{Al}$ was performed via Penning-Trap Mass Spectrometry (PTMS) using TRIUMF's Ion Trap for Atomic and Nuclear science (TITAN). This measurement was facilitated by the use of TRIUMF's new Ion-Guide Laser Ion Source (IG-LIS), which reduced $A=24$ isobaric contamination in the delivered beam by nearly six orders of magnitude. The measured mass excess was found to be $\mathrm{\ensuremath{\Delta}}=\ensuremath{-}48.86(23)$ keV, which is five times more precise than the value quoted in the most recent atomic mass evaluation. When combined with the relevant $^{24}\mathrm{Al}$ excitation energy, and a recent measurement of the $^{23}\mathrm{Mg}$ mass, the astrophysical $^{23}\mathrm{Mg}{(p,\ensuremath{\gamma})}^{24}\mathrm{Al}$ reaction resonance energy is extracted as ${E}_{r}=480.8(14)$ keV. The presented value shows a $2\ensuremath{\sigma}$ disagreement with the direct measurement of this quantity by the DRAGON recoil spectrometer.

Penning trap mass measurements utilizing highly charged ions as a path to benchmark isospin-symmetry breaking corrections inRb74

Penning trap mass measurements of neutron-deficient Rb isotopes have been performed at TRIUMF's Ion Trap for Atomic and Nuclear Science (TITAN) facility by utilizing highly charged ions (HCIs). As imperative for a new approach with significant gain in measurement precision, experimental procedures, and systematic uncertainties are discussed in detail. Among the investigated nuclides, the superallowed nuclear $\ensuremath{\beta}$ emitter $^{74}\mathrm{Rb}$ will especially benefit from the advantage offered by HCI because the limited attainable precision owing to its short half-life $({T}_{1/2}=65$ ms) represents a challenge for conventional Penning trap mass spectrometry. Motivated by an updated ${Q}_{\mathrm{EC}}$ value for $^{74}\mathrm{Rb}$ of 10 416.8(3.9) keV and its large isospin-symmetry breaking corrections, we present a new test to benchmark the consistency between theoretical models of isospin-symmetry breaking corrections in superallowed decays, the conserved vector current hypothesis, and experimental data.

Precision Penning-trap measurement to investigate the role of theCr51(e−,νe)V51Qvalue in the gallium anomaly

A direct $Q$-value measurement has been made at TRIUMF's Ion Trap for Atomic and Nuclear Science (TITAN) for the $^{51}\mathrm{Cr}$(${e}^{\ensuremath{-}}$,${\ensuremath{\nu}}_{e}$)$^{51}\mathrm{V}$ reaction. This electron capture (EC) reaction was used in calibration measurements at the solar neutrino experiments SAGE and GALLEX, and the observed event rate differed from predictions creating the so-called gallium anomaly. Using isotopes delivered by the Isotope Separator and Accelerator (ISAC) facility at TRIUMF and charge breeding them to charge states 5+ and 6+, a $Q$ value of 751.86(55) keV was determined. This represents a 1.3$\ensuremath{\sigma}$ deviation from the result in the Atomic Mass Evaluation 2012 (AME12) and the value used in the calculated event rate. This deviation is found to be insignificant in context of the gallium anomaly, thus confirming that the predicted event rate has not been overestimated as the result of an erroneous $^{51}\mathrm{Cr}$ EC $Q$ value. Additionally, the absolute masses of each $^{51}\mathrm{Cr}$ and $^{51}\mathrm{V}$ have been independently determined and are in agreement with the AME12 values.

Precision mass measurements of short-lived nuclides for nuclear structure studies at TITAN

TITAN (TRIUMF's Ion Trap for Atomic and Nuclear science) at TRIUMF's rare isotope beam facility ISAC is an advanced Penning trap based mass spectrometer dedicated to precise and accurate mass determinations. An overview of TITAN, the mea- surement technique and a highlight of recent mass measurements of the short-lived nu- clides important to the nuclear structure program at TITAN are presented.

Cooling of highly-charged, short-lived ions for precision mass spectrometry at TRIUMF's Ion Trap for Atomic and Nuclear Science

At TRIUMF's Ion Trap for Atomic and Nuclear Science (TITAN), masses of short-lived nuclides are measured accurately and precisely using Penning trap mass spectrometry. The achievable precision is primarily limited by the radioactive lifetime of the nuclides. To boost the precision TITAN has demonstrated that short-lived isotopes can be charge-bred to higher charge states within 10–100 s of ms using an electron beam ion trap. The charge breeding process increases the energy spread of the ions, which in turn affects the precision and the efficiency. A novel cooler Penning trap (CPET) has been developed to trap and cool highly-charged ions using electrons prior to the precision measurement. A discussion of electron cooling and the current status of CPET will be given.

The on-line charge breeding program at TRIUMF's Ion Trap For Atomic and Nuclear Science for precision mass measurements

TRIUMF's Ion Trap for Atomic and Nuclear science (TITAN) constitutes the only high precision mass measurement setup coupled to a rare isotope facility capable of increasing the charge state of short-lived nuclides prior to the actual mass determination in a Penning trap. Recent developments around TITAN's charge breeder, the electron beam ion trap, form the basis for several successful experiments on radioactive isotopes with half-lives as low as 65 ms and in charge states as high as 22+.

Design of a β-detector for TITAN-EC and the first electron-capture branching ratio measurement in a Penning trap

At TRIUMF's ion trap for atomic and nuclear science (TITAN) a new experimental technique is being developed to measure electron-capture branching ratios of intermediate nuclei in double-β decays. The key feature of this novel technique is the use of an open access Penning trap. Radioactive ions are stored inside the trap while their decays are observed. X-rays following an electron capture are detected by x-ray detectors radially installed around the trap. Electrons originating from β-decays are guided out of the trap by the Penning trap's strong magnetic field where they are then detected by a Si-detector. Detailed simulations have been performed to determine the size and characterize the efficiency of this detector. During a beam time with radioactive 107In this β-detector has been used and for the first time an electron capture branching ratio has been determined with this novel technique of in-trap decay spectroscopy.

TITAN-EBIT — charge breeding of radioactive isotopes for high precisionmass measurements

TRIUMF's Ion Trap for Atomic and Nuclear science (TITAN) is a multi-ion trap facility with the goal of high precision mass measurements of radio-nuclides. TITAN is coupled to the ISAC on-line facility at TRIUMF, Vancouver, Canada, and consists of a Radio-Frequency Quadrupole (RFQ) buncher and cooler, an Electron Beam Ion Trap (EBIT), a Cooler Penning Trap (CPET), presently under construction and installation planned for 2011, and the Measurement Penning Trap (MPET). To date the TITAN EBIT has been used for charge breeding of stable and radioactive isotopes. In this paper we report the successful injection and extraction of stable Na and radioactive 25Na. Preliminary emittance measurements have been completed and the emittance in the vertical direction was found to be ϵrms = 15.7±0.5πmm-mrad at a beam energy of 1.95 keV.

Direct Mass Measurement of the Four-Neutron Halo NuclideHe8

A high-precision Penning trap mass measurement of the exotic 8He nuclide (T(1/2)=119 ms) has been carried out resulting in a reduction of the uncertainty of the halo binding energy by over an order of magnitude. The new mass, determined with a relative uncertainty of 9.2 x 10(-8) (deltam=690 eV) is 13 keV less bound than the previously accepted value. The mass measurement is of great relevance for the recent charge-radius measurement of 8He [P. Mueller, Phys. Rev. Lett. 99, 252501 (2007).10.1103/PhysRevLett.99.252501]. The 8He mass is the first result from the newly-commissioned Penning trap: TITAN (TRIUMF's Ion Trap for Atomic and Nuclear science) at the ISAC (Isotope Separator and Accelerator) radioactive beam facility at TRIUMF.

Mass measurements on highly charged radioactive ions, a new approach to high precision with TITAN

TITAN (TRIUMF's Ion Trap for Atomic and Nuclear science) is a system of multiple ion traps installed at the radioactive ion beam facility ISAC. The uniqueness of the system lies in the combination of different kinds of ion traps nowhere else available, and the coupling of this system to ISAC as a source of the most intense radioactive beams of very exotic nuclei worldwide. ISAC is now been operational for more than 5 years, and has been proven to be able to deliver a broad variety of radioactive species with unsurpassed production yields, making it the facility of choice for a next generation ion trap facility, like TITAN. The physics goals of TITAN are manifold, but the emphasis lies on the test of the Standard Model via the determination of the V ud CKM matrix element, nuclear structure and halo-nuclei investigations, and nuclear astrophysics by providing precise and accurate mass measurements.