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Objective. The results of a follow-up experiment investigating a novel method for sub-milimetre range verification (RV) in proton therapy (PT) are presented. Approach. The method consists of implanting a hadron tumour marker (HTM) near the planned treatment volume, and measuring the γ -ray signals emitted as a result of activation by the proton beam. These signals are highly correlated with the energy of the beam impinging on the HTM and can provide an absolute measurement of the range of the beam relative to the position of the HTM, which is independent of any uncertainties in beam delivery. Main results. Three candidate HTM materials were identified and combined into a single composite HTM, which makes use of the strongest reaction in each material. The setup of the previous experiment was improved on by using high-purity germanium detectors to measure the γ -ray signal with a higher resolution than was previously achieved. A PMMA phantom was also used to simulate the γ -ray background from tissue activation. HTM RV using the data collected in this study yielded range measurements whose average deviation from the expected value was 0.13(22)mm. Significance. Range uncertainty in PT limits the prescribed treatment plan for cancer patients with large safety margins and constrains the direction of the proton beam in relation to any organ at risk. The sub-milimetre range uncertainty achieved in this study using HTM RV, if implemented clinically, would allow for a reduction in the size of safety margins, increasing the therapeutic window for PT. [ABSTRACT FROM AUTHOR]

In this work, a new method of range verification for proton therapy (PT) is experimentally demonstrated for the first time. If a metal marker is implanted near the tumour site, its response to proton activation will result in the emission of characteristic γ rays. The relative intensity of γ rays originating from competing fusion-evaporation reaction channels provides a unique signature of the average proton energy at the marker, and by extension the beam's range, in vivo and in real time. The clinical feasibility of this method was investigated at the PT facility at TRIUMF with a proof-of-principle experiment which irradiated a naturally-abundant molybdenum foil at various proton beam energies. Delayed characteristic γ rays were measured with two Compton-shielded LaBr3 scintillators. The technique was successfully demonstrated by relating the relative intensity of two γ-ray peaks to the energy of the beam at the Mo target, opening the door to future clinical applications where the range of the beam can be verified in real time. [ABSTRACT FROM AUTHOR]

The half-life of the superallowed Fermi β + emitter 14 O was determined to high precision via a direct β counting experiment performed at the Isotope Separator and Accelerator (ISAC) facility at TRIUMF. The result, T 1 / 2 ( 14 O) = 70619.2(76) ms, is consistent with, but is more precise than, the world average obtained from 11 previous measurements. Combining the 14 O half-life deduced in the present work with the previous most precise measurements of this quantity leads to a reduction in the overall uncertainty, by nearly a factor of 2. The new world average is T 1 / 2 ( 14 O) = 70619.6(63) ms with a reduced χ 2 value of 0.87 obtained from 8 degrees of freedom. [ABSTRACT FROM AUTHOR]

Monte Carlo simulations are widely used in nuclear physics to model experimental systems. In cases where there are significant unknown quantities, such as energies of states, an iterative process of simulating and fitting is often required to describe experimental data. We describe a Bayesian approach to fitting experimental data, designed for data from a 12Be(d,p) reaction measurement, using simulations made with GEANT4. Q-values from the 12C(d,p) reaction to well-known states in 13C are compared with simulations using BayesOpt. The energies of the states were not included in the simulation to reproduce the situation for 13Be where the states are poorly known. Both cases had low statistics and significant resolution broadening owing to large proton energy losses in the solid deuterium target. Excitation energies of the lowest three excited states in 13C were extracted to better than 90 keV, paving a way for extracting information on 13Be. [ABSTRACT FROM AUTHOR]

The low-energy electromagnetic structure of 110Cd was studied using safe-energy Coulomb excitation at the Heavy Ion Laboratory, University of Warsaw. The preliminary results on the quadrupole deformation of lowlying 0+ states in 110Cd are presented and compared to the recent beyond mean-field and General Bohr Hamiltonian calculations. [ABSTRACT FROM AUTHOR]

The level structure of 98Ru was investigated via -ray spectroscopy following the β+/electron capture decay of 98Rh and with the 100Ru(p; t)98Ru reaction. Additional -ray transitions from low-lying levels were observed and spin-parity assignments of some key states were clarified, permitting the assignment of the 0+2 band and the band. The energies of the states in these bands fit well into the systematic trends observed in the heavier isotopes. The results are interpreted with the aid of beyond-mean-field calculations performed within the self-consistent configuration mixing method. [ABSTRACT FROM AUTHOR]

An array of 128 CsI(Tl) charged particle detectors providing nearly 4 π coverage has been developed at Simon Fraser University (SFU) and commissioned at TRIUMF, Canada's particle accelerator center. The new CsI ball array replaces a previous 24-detector array and offers improved charged particle detection efficiency and discrimination between reaction channels due to its increased angular coverage. A technical overview of the CsI ball array, as well as commissioning data including measurements of the charged particle detection efficiency, is presented. [ABSTRACT FROM AUTHOR]

Proton inelastic scattering off a neutron halo nucleus, 11 Li, has been studied in inverse kinematics at the IRIS facility at TRIUMF. The aim was to establish a soft dipole resonance and to obtain its dipole strength. Using a high quality 66 MeV 11 Li beam, a strongly populated excited state in 11 Li was observed at E x = 0.80 ± 0.02 MeV with a width of Γ = 1.15 ± 0.06 MeV . A DWBA (distorted-wave Born approximation) analysis of the measured differential cross section with isoscalar macroscopic form factors leads us to conclude that this observed state is excited in an electric dipole (E1) transition. Under the assumption of isoscalar E1 transitions, the strength is evaluated to be extremely large amounting to 30 ∼ 296 Weisskopf units, exhausting 2.2 % ∼ 21 % of the isoscalar E1 energy-weighted sum rule (EWSR) value. The large observed strength originates from the halo and is consistent with the simple di-neutron model of 11 Li halo. [ABSTRACT FROM AUTHOR]

Over a 12 year period, the 8β γ-ray spectrometer at the TRIUMFISAC facility was a world unique device for β-decay studies. Equipped with a variety of auxiliary devices, it was used in studies of Fermi superallowed β+ emitters, and nuclear structure studies far from stability and those employing high-statistics measurements. In the present contribution, this latter use is highlighted with examples of recent data obtained in the decay of 122Cs to 122Xe. The 8β spectrometer was replaced with the much more powerful GRIFFIN facility in 2014, ensuring world-leading capability for γ-ray spectroscopy following β decay at TRIUMF-ISAC for the next generation. Examples that highlight GRIFFIN's capabilities are given. [ABSTRACT FROM AUTHOR]

Excited states in 98Ru were investigated using γ -ray spectroscopy following the β -decay of 98Rh, and via the 100Ru(p , t) reaction. Combining the results from the two experiments, two states were revised to have spin-parity of 4 + and subsequently assigned to the 0 2 + and " γ " bands, respectively. The observed structures in 98Ru are suggested to be deformed and rotational, rather than spherical and vibrational, and fit well into the systematics of these excitations in the Ru isotopes. The 0 2 + excitation is suggested as a shape coexisting configuration. This observation eliminates some of the last remaining candidates for nearly harmonic vibrational nuclei in the Z ≈ 50 region. Beyond-mean-field calculations are presented that support shape coexistence throughout the Ru isotopes with N = 52 –62, and suggest a smooth evolution of the shapes. [ABSTRACT FROM AUTHOR]

We used a high-resolution magnetic spectrograph to study neutron pair-correlated 0 + states in 136Ba, produced via the Ba 138 (p , t) reaction. In conjunction with state-of-the-art shell model calculations, these data benchmark part of the dominant Gamow-Teller component of the nuclear matrix element (NME) for 136Xe neutrinoless double beta (0 ν β β) decay. We demonstrate for the first time an evaluation of part of a 0 ν β β decay NME by use of an experimental observable, presenting a new avenue of approach for more accurate calculations of 0 ν β β decay matrix elements. [ABSTRACT FROM AUTHOR]

A 52Cr(p,t)50Cr two-neutron pickup reaction was performed using the Q3D magnetic spectrograph at the Maier-Leibnitz-Laboratorium in Garching, Germany. Excited states in 50Cr were observed up to an excitation energy of 5.3 MeV. Despite significantly increased sensitivity and resolution over previous work, no evidence of the previously assigned first excited 0+ state was found. As a result, the 0+2 state is reassigned at an excitation energy of Ex=3895.0(5) keV in 50Cr. This reassignment directly impacts direct searches for a nonanalog Fermi &#946+ decay branch in 50Mn. These results also show better systematic agreement with the theoretical predictions for the 0+ state spectrum in 50Cr using the same formalism as the isospin-symmetry-breaking correction calculations for superallowed nuclei. The experimental data are also compared to ab-initio shell-model predictions using the IM-SRG formalism based on NN and 3N forces from chiral-EFT in the pf-shell for the first time. [ABSTRACT FROM AUTHOR]

The β-decay half-lives of 128-130Cd have been measured with the newly commissioned GRIFFIN γ-ray spectrometer at the TRIUMF-ISAC facility. The time structures of the most intense γ rays emitted following the β decay were used to determine the half-lives of 128Cd and 130Cd to be T1/2=246.2(21) ms and T1/2=126(4) ms, respectively. The half-lives of the 3/2+ and 11/2− states of Cd129 were measured to be T1/2(3/2+)=157(8) ms and T1/2(11/2-)=147(3) ms. The half-lives of the Cd isotopes around the N=82 shell closure are an important ingredient in astrophysical simulations to derive the magnitude of the second r-process abundance peak in the A∼130 region. Our new results are compared with recent literature values and theoretical calculations. [ABSTRACT FROM AUTHOR]