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We performed TRIUMF in situ measurements of the levels and kinetics of radiation-induced attenuation (RIA) caused by protons in different bulk optical glasses. Two SCHOTT radiation-hardened glasses (doped with Cerium) and six standard optical glasses (without Cerium) have been characterized. We compared the proton RIA kinetics with those resulting from in situ X-ray irradiations performed at dose and dose rate equivalent to the proton testing ones. The RIA spectra and kinetics are quite comparable in both cases, showing that X-rays can efficiently be used to estimate the RIA caused by protons. To better discuss the differences, we performed Monte Carlo calculations with GEANT4 of the energy deposition coefficient for each glass, according to its composition, and for the different beams. We complete our experimental characterization by comparing our data with those measured by the European Space Agency on the same glasses after $\gamma $ -irradiation. Protons, X-rays and $\gamma $ -rays cause RIA with very close spectral dependences, producing the same defects at similar concentration levels. We also demonstrated that the optimized setup for the in situ RIA characterization of bulk materials is very suitable for measurements under collimated particles beam. [ABSTRACT FROM AUTHOR]

Abstract: A proof-of-principle approach for the production of intense (~[10.sup.8]/s) radioactive ion beams, which differs from the standard ISOL (Isotope Separation On-Line) technique, has been demonstrated successfully using [sup.11]C at [...]

We investigated the potential of a multimode (50- $\mu \text{m}$ core diameter) nitrogen doped silica-based optical fiber for X-rays, protons, and $\gamma $ -rays radiation detection and dosimetry. X-rays results confirm that this N-doped fiber presents a strong radioluminescence (RL) around 550 nm when exposed to radiation. The RL observed from a few centimeter long samples linearly depend on the dose rate at least in the 1-mGy/s–50-Gy/s range. Low dose rate $\gamma $ -ray t ests demonstrate the radiation detection at dose rate as low as $40~\mu $ Gy/s with a 2-m-long fiber sample. This fiber is also associated with an optically stimulated luminescence (OSL) when exposed to a 1064-nm laser light postirradiation. This OSL signature provides shortly after the irradiation a precise estimation of the accumulated dose at least in the 1-Gy–10-kGy range. Under proton exposure, we benchmarked the performances of the N-doped fiber with the ones of a conventional Markus chamber used by the TRIUMF proton-therapy team. This comparison highlights the potential of the small-size N-doped fiber to partially overcome the known limitations of commercial fiber-based dosimeters for medical applications. The obtained results are very promising for the future design of more complex spatially resolved beam monitoring systems. [ABSTRACT FROM AUTHOR]

We discuss upsets in erased floating gate cells, due to large threshold voltage shifts, using statistical distributions collected on a large number of memory cells. The spread in the neutral threshold voltage appears to be too low to quantitatively explain the experimental observations in terms of simple charge loss, at least in SLC devices. The possibility that memories exposed to high energy protons and heavy ions exhibit negative charge transfer between programmed and erased cells is investigated, although the analysis does not provide conclusive support to this hypothesis. [ABSTRACT FROM PUBLISHER]

We investigate the potential of innovative optical fiber bulk materials made by the sol-gel technique for real-time proton beam monitoring. Those types of glass are made of amorphous silica ( a -SiO2) doped with either Copper (Cu) or Cerium (Ce) ions. These optimized materials possess very interesting light emission properties when exposed to protons. For both types of glasses, online monitoring of the strong radiation-induced luminescence (RIL) allows to monitor the time evolution of the proton flux with ms resolution and the cumulated proton fluence can be precisely deduced by integrating the RIL signal. Furthermore, we showed that both samples present optically-stimulated luminescence (OSL) that could be exploited shortly after the end of the irradiation to reconstruct the cumulated fluence too. Preliminary tests presented in this paper have been performed at TRIUMF facility with high energy (30 - 63 MeV) protons at flux and fluences representative of proton therapy treatments. Obtained results demonstrate the potential of the developed optical materials for proton beam monitoring and permits to identify the needs for future experiments on microstructured fibers elaborated from these optical materials. [ABSTRACT FROM PUBLISHER]

The low-energy proton energy spectra of all shielded space environments have the same shape. This shape is easily reproduced in the laboratory by degrading a high-energy proton beam, producing a high-fidelity test environment. We use this test environment to dramatically simplify rate prediction for proton direct ionization effects, allowing the work to be done at high-energy proton facilities, on encapsulated parts, without knowledge of the IC design, and with little or no computer simulations required. Proton direct ionization (PDI) is predicted to significantly contribute to the total error rate under the conditions investigated. Scaling effects are discussed using data from 65-nm, 45-nm, and 32-nm SOI SRAMs. These data also show that grazing-angle protons will dominate the PDI-induced error rate due to their higher effective LET, so PDI hardness assurance methods must account for angular effects to be conservative. We show that this angular dependence can be exploited to quickly assess whether an IC is susceptible to PDI. [ABSTRACT FROM PUBLISHER]

A series of astrophysical measurements was recently completed at TRIUMF, related to the unknown total rate of the 21Na(p, γ)22Mg reaction. With a high intensity 21Na beam from the ISAC facility, the DRAGON recoil mass spectrometer was used to directly measure seven resonances at center of mass energies from to 1135 keV and determine their respective contributions to the 21Na(p, γ)22Mg reaction rate in novae and x-ray bursts, as well as their impact on 22Na production in novae. This study also allowed the investigation of different excited states in 22Mg; proposed decays and spin assignments are given for the 6246, 6329, and 6609 keV levels. [Copyright &y& Elsevier]

A novel technique for a high-precision large acceptance determination of the Bragg angle in crystal x-ray spectroscopy is presented and demonstrated. The method exploits visible light beams as fiducials reflected on the x-ray crystal’s surface to ensure exact knowledge of the position on the crystal at which the x rays are reflected, replacing entrance slits, thus making flat crystals suitable for low x-ray fluxes. It can be shown that many error sources arising from uncertainties in the determination of geometrical properties are eliminated in this way. A flat crystal x-ray spectrometer based on this technique has been designed, built, and tested using the most precisely known wavelengths emitted by highly charged ions, namely H- and He-like argon. The result for the 1s2p 1P1→1s2 1S0 w-line of He-like argon exhibits a statistical uncertainty of 3.8 ppm and an estimated systematic error of about 3 ppm, thus becoming the most accurate measurement of the He-like resonance transition in highly charged ions. It is shown that achieving a systematic error of below 1 ppm is feasible with this method. Therefore, our technique should allow reaching total accuracies approaching 1 ppm on transitions of mid-Z highly charged ions, which would provide challenging tests for state-of-the-art theoretical predictions. [ABSTRACT FROM AUTHOR]

The dielectronic recombination resonance (DRR) processes for highly charged krypton ions have been investigated through simultaneously observing the x-ray emission and the ions extracted at the Heidelberg EBIT while slowly scanning the electron beam energy. It was found that at their DR resonance electron energies, the yield of the He-like krypton ions was substantially reduced, whereas that of the Li-like krypton ions was correspondingly increased. At slightly higher electron energies similar features were observed for the Li- and Be-like krypton ions. From the observed ratios of the Li-like/He-like krypton ion currents, we have deduced the dielectronic recombination (DR) strength for the He-like ions, which was found to be in reasonable agreement with theoretical calculations. We have also concluded from the present experiments that the DRR processes can be used to modify the ion charge state distributions and to concentrate the extracted ion currents into particular charge states. This is particularly important for future charge breading experiments with short-lived radioactive isotopes. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Background: 11Li is one of the most studied halo nuclei. The fusion of 11Li with 208Pb is the subject of a number of theoretical studies with widely differing predictions, ranging over four orders of magnitude, for the fusion excitation function. Purpose: The purpose was to measure the excitation function for the 11Li + 208Pb reaction. Methods: A stacked foil and degrader assembly of 208Pb targets was irradiated with a 11Li beam producing center-of-target beam energies from above-barrier to near-barrier energies (40-29 MeV). The intensity of the 11Li beam (chopped) was 1250 particles/s and the beam on-target time was 34 h. The α decay of the stopped evaporation residues (EVRs) was detected in an α-detector array at each beam energy in the beam-off period (the beam was on for ≤ 5 ns and then off for 170 ns). Results: The observed nuclidic yields of 212/215At and 214At are consistent with being produced in the complete fusion of 11Li with 208Pb. The observed yields of 213At appear to be the result of the breakup of 11Li into 9Li + 2n, with the 9Li fusing with 208Pb. The magnitudes of the total fusion cross sections are substantially less than most theoretical predictions. Conclusions: It is possible to measure the EVR production cross sections resulting from the interaction of 11Li with 208Pb using current-generation radioactive beam facilities. Both complete fusion and breakup fusion processes'occur in the interaction of 11Li with 208Pb. An important breakup process leads to the fusion of the 9Li fragment with 208Pb. [ABSTRACT FROM AUTHOR]

Abstract: The DRAGON facility at TRIUMF/ISAC detects reaction products following radiative capture of a hydrogen or helium target nucleus by an accelerated heavy ion. Capture reactions of interest in nuclear astrophysics may have reaction rates 10–14 orders of magnitude lower than the intensity of the incident beam: as well as efficiently transporting the heavy reaction product from the target to a suitable particle detector, the separator must provide most of the suppression of unreacted beam. We describe the features of beam background encountered in a range of proton- and alpha-capture experiments at the DRAGON facility. [Copyright &y& Elsevier]

Abstract: The DRAGON (Detector of Recoils And Gammas Of Nuclear reactions) is used to measure radiative proton and alpha capture reaction rates involving both stable and radioactive, heavy-ion reactants at the TRIUMF-ISAC high intensity radioactive beam facility. Completed in 2001 it has been used for several challenging studies for nuclear astrophysics, e.g. 12C(α, γ)16O, 21Na(p, γ)22Mg, 26gAl(p, γ)27Si and 40Ca(α, γ)44Ti. Since initial operation, a number of improvements have been incorporated which are described here. These include a beam centering monitor based on a CCD camera, a mechanical iris to skim of beam halo, a solid state stripper acting as a charge state booster for beams with A ≳30, beta and gamma detectors to monitor beam intensity and to determine beam contamination in experiments with radioactive beam and the ionization chamber for both recoil identification and isobar separation. [Copyright &y& Elsevier]

Magneto-optical traps provide a cold, compact cloud of radioactive atoms and therefore are an ideal source for use in precision nuclear β decay studies. Optical pumping techniques can add a new dimension to such experiments by efficiently polarizing these samples to ≳99%. Triumf’s experiment E925 is utilizing these techniques to prepare to measure the isospin mixing between the first two Iπ=2+ excited states of 36Ar with the lowest 2+, T=1 isobaric analog state. The spin-polarized 36K β+ decay observables will be measured using Triumf’s neutral atom trap at Isac, Triumf’s isotope separator and accelerator facility. The main purpose is to test isospin mixing models in the s,d-shell needed for determination of the superallowed Fermi strength in 0+ → 0+ decays. [Copyright &y& Elsevier]

Solutions containing a high concentration (0.325-0.995 g/ml) of natural-abundance ammonium heptamolybdate tetrahydrate ((NH(4))(6)Mo(7)O(24))·4H(2)O were irradiated at 13 MeV on a proton-beam cyclotron using a standard liquid target. (94m)Tc was produced via the (94)Mo(p,n)(94m)Tc reaction with measured yields of 110±20 MBq for the highest concentrated solution using 5 μA proton beams for 60 min. Saturation yields of up to 40±6 MBq/μA were achieved. Pertechnetate was isolated from the target mixture with 70.9±0.7% efficiency using a solid-phase extraction resin., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

The p((11)Li, (9)Li)t reaction has been studied for the first time at an incident energy of 3A MeV at the new ISAC-2 facility at TRIUMF. An active target detector MAYA, built at GANIL, was used for the measurement. The differential cross sections have been determined for transitions to the (9)Li ground and first excited states in a wide range of scattering angles. Multistep transfer calculations using different (11)Li model wave functions show that wave functions with strong correlations between the halo neutrons are the most successful in reproducing the observation.

Radiative alpha-particle capture into the first excited, J(pi)=0+ state of 16O at 6.049 MeV excitation energy has rarely been discussed as contributing to the 12C(alpha,gamma)16O reaction cross section due to experimental difficulties in observing this transition. We report here measurements of this radiative capture in 12C(alpha,gamma)16O for center-of-mass energies of E=2.22 MeV to 5.42 MeV at the DRAGON recoil separator. To determine cross sections, the acceptance of the recoil separator has been simulated in GEANT as well as measured directly. The transition strength between resonances has been identified in R-matrix fits as resulting both from E2 contributions as well as E1 radiative capture. Details of the extrapolation of the total cross section to low energies are then discussed [S6.0(300)=25(-15)(+16) keV b] showing that this transition is likely the most important cascade contribution for 12C(alpha,gamma)16O.

The strength of the Ec.m. = 184 keV resonance in the 26gAl(p, gamma)27 reaction has been measured in inverse kinematics using the DRAGON recoil separator at TRIUMF's ISAC facility. We measure a value of omega gamma = 35 +/- 7 microeV and a resonance energy of Ec.m. = 184 +/- 1 keV, consistent with p-wave proton capture into the 7652(3) keV state in 27Si, and discuss the implications of these values for 26GAl nucleosynthesis in typical oxygen-neon white-dwarf novae.

We present experimental data on the state-selective quantum interference between different pathways of photorecombination, namely, radiative and dielectronic recombination, in the KLL resonances of highly charged mercury ions. The interference, observed for well resolved electronic states in the Heidelberg electron beam ion trap, manifests itself in the asymmetry of line shapes, characterized by "Fano factors," which have been determined with unprecedented precision, as well as their excitation energies, for several strong dielectronic resonances.

We have set limits on contributions of scalar interactions to nuclear beta decay. A magneto-optical trap provides a localized source of atoms suspended in space, so the low-energy recoiling nuclei can freely escape and be detected in coincidence with the beta. This allows reconstruction of the neutrino momentum, and the measurement of the beta-nu correlation, in a more direct fashion than previously possible. The beta-nu correlation parameter of the 0(+)-->0(+) pure Fermi decay of (38)K(m) is a =0.9981+/-0.0030+0.0032 / -0.0037, consistent with the standard model prediction a =1.

A new technique, full neutrino momentum reconstruction, is used to set limits on the admixture of heavy neutrinos into the electron neutrino. We measure coincidences between nuclear recoils and positrons from the beta decay of trapped radioactive atoms and deduce the neutrino momentum. A search for peaks in the reconstructed recoil time-of-flight spectrum as a function of positron energy is performed. The admixture upper limits range from 4 x 10(-3) to 2 x 10(-2) and are the best direct limits for neutrinos (as opposed to antineutrinos) for the mass region of 0.7 to 3.5 MeV.