Abstract: Developments at TRIUMF’s isotope separator and accelerator (ISAC) resonance ionization laser ion source (RILIS) in the past years have concentrated on increased reliability for on-line beam delivery of radioactive isotopes to experiments, as well as increasing the number of elements available through resonance ionization and searching for ionization schemes with improved efficiency. The current status of these developments is given with a list of two step laser ionization schemes implemented recently.

Abstract: Radio-frequency (rf) Paul traps operated with multifrequency rf trapping potentials provide the ability to independently confine charged particle species with widely different charge-to-mass ratios. In particular, these traps may find use in the field of antihydrogen recombination, allowing antiproton and positron clouds to be trapped and confined in the same volume without the use of large superconducting magnets. We explore the stability regions of two-frequency Paul traps and perform numerical simulations of small samples of multispecies charged-particle mixtures of up to twelve particles that indicate the promise of these traps for antihydrogen recombination.

Abstract: We present a study of TiO2 single crystals from the point of view of the dopant atom that simultaneously behaves as the probing element. We used gamma-gamma time dependent perturbed angular correlations working with selected tracer elements (111In/ 111Cd, 111mCd/ 111Cd) together to investigate the different behavior of Cd and In dopants, particularly their interaction with point defects in the TiO2 lattice. Results show that the hyperfine interactions observed at 111Cd from 111In or 111mCd decay are quite different. 111In/ 111Cd results show a single site fraction characterized by a quadrupole frequency with asymmetry parameter similar to those observed for the same probe nuclei in bulk TiO2 oxides. Results for 111mCd/ 111Cd reveal two site fractions, one characterized by the same hyperfine parameters to those measured in bulk TiO2 and another fraction characterized by a quadrupole frequency and asymmetry parameters with higher values, as observed in thin TiO2 films and correlated with point defects. The results are discussed emphasizing the differences for Cd and In as defect traps on TiO2.

Abstract: The MEDICIS-PROMED Innovative Training Network under the Horizon 2020 EU program aims to establish a network of early stage researchers, involving scientific exchange and active cooperation between leading European research institutions, universities, hospitals, and industry. Primary scientific goal is the purpose of providing and testing novel radioisotopes for nuclear medical imaging and radionuclide therapy. Within a closely linked project at CERN, a dedicated electromagnetic mass separator system is presently under installation for production of innovative radiopharmaceutical isotopes at the new CERN-MEDICIS laboratory, directly adjacent to the existing CERN-ISOLDE radioactive ion beam facility. It is planned to implement a resonance ionization laser ion source (RILIS) to ensure high efficiency and unrivaled purity in the production of radioactive ions. To provide a highly efficient ionization process, identification and characterization of a specific multi-step laser ionization scheme for each individual element with isotopes of interest is required. The element lutetium is of primary relevance, and therefore was considered as first candidate. Three two-step excitation schemes for lutetium atoms are presented in this work, and spectroscopic results are compared with data of other authors.

Abstract: The Morin transition of very thin Ir-doped α-Fe2O3 films, which is not detectable with conventional magnetization measurements, was studied by conversion electron Mossbauer spectroscopy using a 57Co source and nuclear resonant scattering using a synchrotron light source. It was found that (i) the Morin transition temperature increases as the Ir ratio increases, (ii) it decreases when the film thickness decreases, and (iii) the transition becomes irreversible when Ir ratio is small and the thickness is thin. These tendencies were found reproducible and systematic, although the mechanisms are to be clarified by further studies.

Abstract: We have prepared the 2D spin crossover complexes Fe(L)2Pd(CN)4 (L = py : 1a; py-D5 : 1b and py-15N :1c). 1a has been characterised by 57Fe Mossbauer spectroscopic measurements, single crystal X-ray determination and SQUID measurements. The Mossbauer spectra for 1a indicate that the iron(II) spin states are in high spin states at 298 K and are in low spin states at 77 K. The crystal structures of 1a at 298 K and 90 K also show the high spin state and the low spin state respectively, associated with the Fe(II)-N distances. The spin transition temperature range of 1a is higher than that of Fe(py)2Ni(CN)4 since Pd(II) ions are larger and heavier than Ni(II) ions. SQUID data indicate isotope effects among 1a, 1b and 1c are observed in very small shifts of the transition temperatures probably due to larger and heavier Pd(II) ions. The delicate shifts would be associated with subtle balances between different vibrations around Fe(II) atoms and electronic factors.

Abstract: The Lynch 001 meteorite was found in the Nullarbor Plain region of Western Australia in 1977. This meteorite is classified as an ordinary chondrite of the petrologic group L5/6 that has undergone ‘minor to moderate’ terrestrial weathering. Here, we characterize the Fe-bearing phases in this chondrite using 57Fe Mossbauer spectroscopy carried out over the temperature range 13 K to room temperature (295 K). The paramagnetic doublets of olivine, pyroxene and a superparamagnetic ferric phase dominate the room temperature Mossbauer spectrum. On the basis of the room temperature quadrupole splitting of the olivine component, we estimate its composition to be Fa 30(5). Besides the paramagnetic ferric component, accounting for ∼15 % of the spectral area at room temperature, magnetically ordered ferric phases were also detected. The total relative proportion of the Fe 3+ components allows us to estimate the terrestrial age of Lynch 001 to be 6,500 ± 1,500 yr, consistent with the value of 6,700 ± 1,300 yr determined by 14C dating.

Abstract: This paper presents the results of ionization scheme development for application at the ISOLDE Resonance Ionization Laser Ion Source (RILIS). Two new ionization schemes for mercury are presented: a three-step three-resonance ionization scheme, ionizing via an excitation to a Rydberg level and a three-step two-resonance ionization scheme, with a non-resonant final step to the ionization continuum that corresponded to a factor of four higher ionization efficiency. The efficiency of the optimal mercury ionization scheme was measured, together with the efficiency of a new three-step three resonance ionization scheme for tellurium. The efficiencies of the mercury and tellurium ionization schemes were determined to be 6 % and >18 % respectively.

Abstract: If suitably prepared, hematite (αFe2O3)-based materials may be effective photocatalysts under visible light. Doping hematite with cations is assumed to improve the chemical photocatalyst performance of hematite. To check for these effects, the catalytic efficiency under visible radiation of the pure, Co-, Ni-, Cu-, or Zn-doped nanosized hematite samples was tested on the degradation of the indigo carmine dye, as a model molecule to simulate a generic organic substrate. These semiconductors with photocatalyst activity were first characterized by powder X-ray diffractometry, Mossbauer spectroscopy, scanning electron microscopy coupled with energy dispersive X-ray spectrometer, diffuse reflectance spectroscopy and by energy dispersive X-ray fluorescence. The most efficient photocalysts for the indigo carmine dye degradation were the Cu- and Zn-doped hematite samples. The relatively higher photocatalytic activity of these two samples are interpreted as being due to their relatively higher ability, among the tested semiconductors, to absorb the visible light, efficient charge separation and e−-transference.

Abstract: A novel sample environment enabling optical pump – nuclear resonance probe experiments has been installed at the beamline P01, Petra III, DESY Hamburg. This set-up has been used to investigate optically induced spin state changes of spin crossover (SCO) complexes by nuclear resonant scattering immediately after excitation by an optical laser pulse. Here, we report the technical details as well as first results of the experiments performed at 290 K and 80 K on the SCO complexes [Fe (NH2trz)3]Cl2 and [Fe(PM-BiA)2(NCS)2], respectively. The 57Fe-enriched SCO complexes were excited by a 531 nm laser with a pulse length < 100 ps. Evaluation of the nuclear forward scattering data clearly indicate the presence of high spin (HS) states when the complexes are excited by laser pulses and a pure low spin (LS) state in the absence of any laser pulse. Furthermore, the dependence of the optically excited HS-fraction has been determined as a function of the average optical power.

Abstract: The beta-detected nuclear magnetic resonance (β-NMR) in liquid H2O has been observed for the first time using a short-lived β-ray emitter 12N (I π = 1+,T 1/2=11 ms). A nuclear spin polarized 12N beam with an energy of about 20 MeV/nucleon was implanted into an enclosed water sample. About 50 % of implanted 12N ions maintained nuclear polarization and exhibited a β-NMR spectrum. The chemical shift of 12N in H2O relative to 12N in Pt was deduced to be −(3.6±0.5) × 102 ppm.

Abstract: We report on progress towards performing precision measurements of parity violation in Yb, in which the theoretical prediction for a strong weak-interaction-induced effect in the 6s2 1S0→ 5d6s3D1 optical transition at 408 nm has already been confirmed, with a measurement of the effect at the ≈10 % level of accuracy. With a new atomic-beam apparatus offering enhanced sensitivity, we are aiming at precisely determining the parity violation observable in Yb, which will allow us to probe the distributions of neutrons in different isotopes, investigate physics beyond the Standard Model, as well as to study intra-nucleus weak interactions, through an observation of the anapole moment of Yb nuclei with nonzero spin. We present the experimental principle employed to probe atomic parity violation, describe our new apparatus, and discuss the attained experimental sensitivity as well as the methods for characterizing systematics in these measurements.

Abstract: Nanometric magnetite (nm-Fe3O4) particles were prepared by the reverse co-precipitation synthesis method, obtaining particle sizes that ranged from 4 to 8.5 nm. In their synthesis, the concentration of iron salts of ferric nitrate, Fe(NO3)3⋅9H2O, and ferrous sulfate, FeSO4⋅7H2O, were varied relative to the chemical reaction volume and by using different surfactants such as oleic acid (OA) and hexadecyltrimethylammonium bromide (CTAB). The nm-Fe3O4 particles were characterized by transmission electron microscopy (TEM), Mossbauer spectroscopy (MS), magnetic and X-ray diffraction (XRD) measurements. Typical asymmetrical and/or broad lines shapes appeared in all Mossbauer spectra of the as prepared samples suggesting strong magnetic inter-particle interactions, reducing these interactions to some extent by gentle mechanical grinding. For the smallest particles, maghemite instead of magnetite was the main preparation product as low temperature Mossbauer and magnetic measurements indicated. For the intermediate and largest particles a mixture of magnetite and maghemite phases were produced as the saturation magnetization values of MS ∼ 60 emu/g indicated; these values were measured for most samples, independently of the coating surfactant concentration, and according to the ZFC-FC curves the blocking temperatures were 225K and 275K for the smallest and largest magnetite nanoparticles, respectively. The synthesis method was highly reproducible.

Abstract: Synchrotron-Radiation-based $^{\mathrm {149}}$ Sm Mossbauer spectroscopy was applied to Sm intermetallics, SmBe13 and SmTi2Al20. Temperature dependence of the Mossbauer parameters in SmBe13 indicate the Sm valence state is purely trivalent. SmBe13 also showed second-order Doppler shift in synchrotron-radiation-based $^{\mathrm {149}}$ Sm Mossbauer spectroscopy. The Mossbauer parameters obtained in SmTi2Al20 suggest that the Sm valence is fluctuating and the magnitude of the magnetic moment is reduced by hybridization between 4f and conduction electrons and/or effect of crystal electric field.

Abstract: A simple external optical feedback system has been applied to a distributed feedback quantum cascade laser (DFB QCL) for cavity ring-down spectroscopy (CRDS) and a clear effect of feedback was observed. A long external feedback path length of up to 4m can decrease the QCL linewidth to around 50kHz, which is of the order of the transmission linewidth of our high finesse ring-down cavity. The power spectral density of the transmission signal from high finesse cavity reveals that the noise at frequencies above 20kHz is reduced dramatically.

Abstract: In this study, Fe-1250Mn-110C-170Cr-040Mo-040Si-050(max)P-050(max)S (Hadfield alloy) and Fe-284Mn-086C-163Al-042Cu-180Mo-159Si-060W (Fermanal alloy) (Wt %) in the aged condition were compared in terms of its tribological and microstructural properties The x-ray diffraction (XRD) patterns were refined with the lines of the austenitic γ-phase, Chromium Iron Carbide (Cr2Fe14C), Iron Carbide (Fe2C), and Iron Oxide (Fe0974O (II)) for the Hadfield alloy, and the lines of the austenitic γ-phase, martensite (M), Mn11Al09 phase and iron carbide (Fe7C3) for the Fermanal alloy Mossbauer spectra were fit with two sites for the Hadfield alloy, which displayed as a broad singlet because of the austenitic disordered phase, and had a magnetic hyperfine field distribution, which corresponds to the Cr2Fe14C ferromagnetic carbides found by XRD There were two paramagnetic sites, a singlet, which corresponds to the austenite disordered phase, and a doublet, which can be attributed to the Fe7C3 carbide The obtained Rockwell C hardness for aged Hadfield and Fermanal alloys were 43786 and 50018 HRc, respectively

Abstract: Biogenic transformations of iron-containing minerals synthesized ferrihydrite, magnetite and hydrothermal siderite by anaerobic alkaliphilic bacterium Fuchsiella ferrireducens (strain Z-7101T) were studied by 57Fe Mossbauer spectroscopy. Mossbauer investigations of solid phase samples obtained after microbial transformation were carried out at room temperature and at 82 K. It was found that all tested minerals transformed during bacterial growth. In the presence of synthesized ferrihydrite, added as an electron acceptor, a mixture of large (more than 100 nm) and small (∼5 nm) particles of magnetically ordered phase and siderite was formed. Synthesized magnetite that contains both Fe3+ and Fe2+ forms could serve as electron acceptor as well as an electron donor for F.ferrireducens growth. As a result of its biotransformation, no siderite formation was observed while small particles of magnetite were formed. In the case of the addition of siderite as an electron donor formation of a small amount of a new phase containing Fe2+ caused by recrystallization of siderite during bacterial growth was detected.

Abstract: [Fe{N(entz)3}2](ClO4)2 (N(entz)3 = tris(2-(1H-tetrazol-1-yl)ethyl)-amine) is a 2D FeII coordination polymer built from a tris-1-R tetrazole building block. This thermochromic FeII complex which was investigated by variable temperature 57Fe Mossbauer spectroscopy (78–300 K) displays on cooling a complete, abrupt and hysteretic spin transition at $T_{c}^{\uparrow } = 170(1)$ K and $T_{c}^{\downarrow } = 149(1)$ K. The reversibility of the spin transition over several thermal cycles was deduced from SQUID magnetometry. Differential scanning calorimetry reveals a reversible first order phase transition on cooling below room temperature, with entropy data consistent with the highly cooperative character of the spin transition.

Abstract: The NPDGamma experiment measures the parity-violating (PV) gamma asymmetry from polarized cold neutrons captured on protons at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory (ORNL). The (PV) neutron spin asymmetry A γ of photons from polarized cold neutron capture on protons is proportional to the ΔI=1 long range weak meson coupling $h_{\pi }^{1}$ between nucleons in the hadronic weak interaction (HWI). Liquid para-hydrogen production data taking concluded in April 2014 and once the background aluminum asymmetry measurements are complete, the PV asymmetry A γ can be extracted. Preliminary results of the analysis of A γ are presented.

Abstract: The effect of the FePO4 material phase transformation in the direct selective oxidation of methane to methanol was studied using various oxidants, i.e. O2, H2O and N2O. The phases of the heterogeneous catalyst applied, before and after the reactions, were characterized by M¨ossbauer spectroscopy. The main reaction products were methanol, carbon monoxide and carbon dioxide, whereas formaldehyde was produced in rather minute amounts. The Mossbauer spectra showed the change of the initial catalyst material, FePO4 (tridymite-like phase (tdm)), to the reduced metal form, iron(II) pyrophosphate, Fe2P2O7, and thereafter, the material phase change was governed by the oxidation with individual oxidizing species.Mossbauer spectroscopy measurements applied along with X-ray diffraction (XRD) studies on fresh, reduced and spent catalytic materials demonstrated a transformation of the catalyst to a mixture of phases which depended on operating process conditions. Generally, activity was low and should be a subject of further material optimization and engineering, while the selectivity towards methanol at low temperatures applied was adequate. The proceeding redox mechanism should thus play a key role in catalytic material design, while the advantage of iron-based heterogeneous catalysts primarily lies in them being comparably inexpensive and comprising non-critical raw materials only.

Abstract: The X. international workshop on “Application of Lasers and Storage Devices in Atomic Nuclei Research” took place in Poznan in May 2016. It addressed the latest experimental and theoretical achievements in laser and ion trap-based investigations of radionuclides, highly charged ions and antiprotons. The precise determination of atomic and nuclear properties provides a stringent benchmark for theoretical models and eventually leads to a better understanding of the underlying fundamental interactions and symmetries. This article addresses some general trends in this field and highlights select recent achievements presented at the workshop. Many of these are covered in more detail within the individual contributions to this special issue of Hyperfine Interactions.

Abstract: The archaeological site Pedra do Cantagalo I is a sandstone shelter displaying rupestrian inscriptions. It is located in the rural area of the municipality of Piripiri, in the northern region of the Piaui state, Brazil. The site was found as being originally decorated with more than 1,900 prehistoric rupestrian paintings, along with engravings, lithics, ceramic fragments and mineral pigments forming reddish and yellowish ochres. Materials of these ochres, collected from recent excavations in this archaeological site, were analyzed by energy dispersive X-ray fluorescence (EDXRF); backscattering and transmission 57Fe-Mossbauer spectroscopy at 298 K and 25 K and powder X-ray diffraction (XRD), in an effort to assess the chemical and mineralogical characteristics of these sources of pigments that composed the ancient paint materials of the site. The iron contents (expressed as Fe 2O3) for the reddish ochres were found to range from ∼60 to ∼68 mass%; for the yellowish ochres the corresponding content was ∼34 mass%, as determined by EDXRF. From the Mossbauer spectra for these red ochre samples, hematite (αFe 2O3) or a mixture of hematite and goethite (αFeOOH) were identified. Actually, the spectra at room temperature for the yellow ochres are rather complex, as it is usual for most soil clay materials. At least part of the intense central doublet was assumed to be from superparamagnetic iron oxides in very small particles. The Mossbauer patterns at 25 K allowed confirming this assumption, as the superparamagnetic relaxation effects were virtually suppressed; the spectral contributions due to goethite could be thus more easily separated.

Abstract: The Collinear Resonance Ionization Spectroscopy (CRIS) experiment, located at the ISOLDE facility, has recently performed high-resolution laser spectroscopy, with linewidths down to 20 MHz. In this article, we present the modifications to the beam line and the newly-installed laser systems that have made sensitive, high-resolution measurements possible. Highlights of recent experimental campaigns are presented.

Abstract: The PIENU experiment aims to measure the branching ratio of the charged pion decay with precision of < 0.1 %. This measurement is much sensitive to search for massive neutrinos coupled to electrons in ${\pi }^{+}{\rightarrow }e^{+}{ u }_{e}$ decay. The initial analysis was completed and the upper limit on the neutrino mixing parameter |U e i |2 in the neutrino mass range of 0 to 55 MeV/c 2 was improved by a factor of 1.5, and the sensitivity for the mass range of 68 to 129 MeV/c 2 was improve by a factor of up to 4.

Abstract: Maraging400-like alloys were made by arc-melting iron with the alloy elements (i.e., Ni, Co, Ti and Mo), followed by a high temperature heat-treatment for solubilization. The solubilized alloys were further heat-treated (480 °C and 580 °C, by 3 h), for aging. The samples were finely characterized by X-ray diffraction (Rietveld refinement), Mossbauer spectroscopy and magnetization techniques. The results revealed that the as-solubilized sample is martensitic and ferromagnetic. Its residual induction and coercive field increase monotonically with the maximum applied field of a magnetization minor loop and both curves presented very similar shapes. The area of the minor loops varies parabolically with this maximum applied field. The aging induced an atomic rearrangement in the martensite phase, involving change in the composition and lattice parameters, reversion of austenite and the formation of the Fe 3 Mo 2 intermetallic compound. Comparisons are presented between the results obtained by us for these alloys and those obtained for Maraging-350 steel samples.

Abstract: Zinc-iron oxide nanoparticles (ZnxFe3−xO4 and δ-ZnxFe1−xOOH) were successfully synthesized by room temperature chemical reaction of a solution containing ZnCl2 and FeCl2 in the presence of gelatin. The composition of products could be controlled by variation of the Zn/Fe mixture ratio of the starting material. ZnxFe3−xO4 nanoparticles were obtained from a solution with a high Zn/Fe ratio, whereas Zn-doped feroxyhyte (δ-ZnxFe1−xOOH) nanoparticles were obtained from a solution with a low Zn/Fe ratio. The ZnxFe3−xO4 nanoparticles were spherical with diameters of approximately 10 nm, and the δ-ZnxFe1−xOOH particles were needle-like with lengths of approximately 100 nm. Mossbauer spectra measured at room temperature indicated superparamagnetic behavior of the nanoparticles, whereas the magnetic components were observed at low temperature. The Zn content of the intermediate species ( $(\text {Zn}^{\text {II}}_{\mathrm {x}}\text {Fe}^{\text {II}}_{\mathrm {1-x}}\text {Fe}^{\text {III}}_{\mathrm {2}}\mathrm {O}_{4})$ ) plays an important role in the oxidation process. When the Zn concentration was high, the content of Fe2+ in the intermediate species was small, and Zn2+ prevented further oxidation of the nanoparticles. When the starting material had low Zn concentration, the amount of Fe2+ in the intermediate species became large and was rapidly oxidized into δ-ZnxFe1−xOOH while rinsing under the ambient atmosphere.

Abstract: MuSEUM is an international collaboration aiming at a new precise measurement of the muonium hyperfine structure at J-PARC (Japan Proton Accelerator Research Complex). Utilizing its intense pulsed muon beam, we expect a ten-fold improvement for both measurements at high magnetic field and zero magnetic field. We have developed a sophisticated monitoring system, including a beam profile monitor to measure the 3D distribution of muonium atoms to suppress the systematic uncertainty.

Abstract: Trivalent iron sulfide (Fe2 S 3) particles were synthesized using a modified polyol method. These particles exhibited a needle-like shape (diameter = 10-50 nm, length = 350-1000 nm) and generated a clear XRD pattern. Mossbauer spectra of the product showed a paramagnetic doublet at room temperature and distributed hyperfine magnetic splitting at low temperature. The Curie temperature of this material was determined to be approximately 60 K. The data suggest that the Fe2 S 3 had a structure similar to that of maghemite (γ-Fe2 O 3) with a lattice constant of a = 10.6 A. The XRD pattern calculated from this structure was in agreement with the experimental pattern and the calculated hyperfine magnetic field was also equivalent to that observed in the experimental Mossbauer spectrum.

Abstract: Laser ablation in liquid is a useful mean of producing nanoparticles, based on both laser ablation (LA) and laser irradiation (LI) effects. In order to investigate the mechanism by which iron carbide nanoparticles are generated in ethanol, iron carbide nanoparticles were produced by LA of an iron block in a flowing ethanol solvent, which enabled separation and collection of the nanoparticles immediately following the process. These same particles were subsequently subjected to LI while suspended in stagnant ethanol. Both the LA and LA/LI nanoparticles were assessed using Mossbauer spectroscopy, X-ray diffraction and transmission electron microscopy. LA in flowing ethanol was found to produce nanoparticles composed of cementite (Fe3C) and other metastable iron carbides with an average size of 16 nm, dispersed in amorphous carbon. LI of the LA nanoparticles suspended in ethanol increased the particle size to 38 nm and changed the composition to pure Fe3C.