Mass measurements near the rr-process path using the Canadian Penning Trap mass spectrometer

The masses of 40 neutron-rich nuclides from Z = 51 to 64 were measured at an average precision of $\delta m/m= 10^{-7}$ using the Canadian Penning Trap mass spectrometer at Argonne National Laboratory. The measurements, of fission fragments from a $^{252}$Cf spontaneous fission source in a helium gas catcher, approach the predicted path of the astrophysical $r$ process. Where overlap exists, this data set is largely consistent with previous measurements from Penning traps, storage rings, and reaction energetics, but large systematic deviations are apparent in $\beta$-endpoint measurements. Differences in mass excess from the 2003 Atomic Mass Evaluation of up to 400 keV are seen, as well as systematic disagreement with various mass models.Comment: 15 pages, 16 figures. v2 updated, published in Physical Review

β-delayed neutron spectroscopy using trapped radioactive ions

A novel technique for β-delayed neutron spectroscopy has been demonstrated using trapped ions. The neutron-energy spectrum is reconstructed by measuring the time of flight of the nuclear recoil following neutron emission, thereby avoiding all the challenges associated with neutron detection, such as backgrounds from scattered neutrons and γ rays and complicated detector-response functions. I+137 ions delivered from a Cf252 source were confined in a linear Paul trap surrounded by radiation detectors, and the β-delayed neutron-energy spectrum and branching ratio were determined by detecting the β- and recoil ions in coincidence. Systematic effects were explored by determining the branching ratio three ways. Improvements to achieve higher detection efficiency, better energy resolution, and a lower neutron-energy threshold are proposed. © 2013 American Physical Society

Tensor interaction limit derived from the α-β-ν̄ correlation in trapped Li8 ions

A measurement of the α-β-ν̄ angular correlation in the Gamow-Teller decay Li8→Be*8+ν̄+β, Be*8→ α+α has been performed using ions confined in a linear Paul trap surrounded by silicon detectors. The energy difference spectrum of the α particles emitted along and opposite the direction of the β particle is consistent with the standard model prediction and places a limit of 3.1% (95.5% confidence level) on any tensor contribution to the decay. From this result, the amplitude of any tensor component CT relative to that of the dominant axial-vector component CA of the electroweak interaction is limited to |CT/CA|\u3c0.18 (95.5% confidence level). This experimental approach is facilitated by several favorable features of the Li8 β decay and has different systematic effects than the previous β-ν̄ correlation results for a pure Gamow-Teller transition obtained from studying He6 β decay. © 2013 American Physical Society

Limit on Tensor Currents from Li 8 β Decay

In the standard model, the weak interaction is formulated with a purely vector-axial-vector (V-A) structure. Without restriction on the chirality of the neutrino, the most general limits on tensor currents from nuclear β decay are dominated by a single measurement of the β-ν¯ correlation in He6 β decay dating back over a half century. In the present work, the β-ν¯-α correlation in the β decay of Li8 and subsequent α-particle breakup of the Be8∗ daughter was measured. The results are consistent with a purely V-A interaction and in the case of couplings to right-handed neutrinos (CT=-CT′) limits the tensor fraction to |CT/CA|2\u3c0.011 (95.5% C.L.). The measurement confirms the He6 result using a different nuclear system and employing modern ion-trapping techniques subject to different systematic uncertainties

Production of radioactive ion beams using the in-flight technique

Reactions with a heavy projectile incident on a light target can be used for the efficient in-flight production of secondary radioactive beams. An overview of this technique is given using data on 17F beams produced via the p(17O, 17F)n and d(16O, 17F)n reactions. With primary 16,17O beam currents of 100 pnA, intensities of up to 2×106 17F/s on target were achieved. Using this beam, the p(17F, α) 14O reaction was measured

Magnetic Resonance Thermometry at 7T for Real-Time Monitoring and Correction of Ultrasound Induced Mild Hyperthermia

While Magnetic Resonance Thermometry (MRT) has been extensively utilized for non-invasive temperature measurement, there is limited data on the use of high field (≥7T) scanners for this purpose. MR-guided Focused Ultrasound (MRgFUS) is a promising non-invasive method for localized hyperthermia and drug delivery. MRT based on the temperature sensitivity of the proton resonance frequency (PRF) has been implemented in both a tissue phantom and in vivo in a mouse Met-1 tumor model, using partial parallel imaging (PPI) to speed acquisition. An MRgFUS system capable of delivering a controlled 3D acoustic dose during real time MRT with proportional, integral, and derivative (PID) feedback control was developed and validated. Real-time MRT was validated in a tofu phantom with fluoroptic temperature measurements, and acoustic heating simulations were in good agreement with MR temperature maps. In an in vivo Met-1 mouse tumor, the real-time PID feedback control is capable of maintaining the desired temperature with high accuracy. We found that real time MR control of hyperthermia is feasible at high field, and k-space based PPI techniques may be implemented for increasing temporal resolution while maintaining temperature accuracy on the order of 1°C

Monitoring quality and coverage of harm reduction services for people who use drugs: a consensus study.

BACKGROUND AND AIMS: Despite advances in our knowledge of effective services for people who use drugs over the last decades globally, coverage remains poor in most countries, while quality is often unknown. This paper aims to discuss the historical development of successful epidemiological indicators and to present a framework for extending them with additional indicators of coverage and quality of harm reduction services, for monitoring and evaluation at international, national or subnational levels. The ultimate aim is to improve these services in order to reduce health and social problems among people who use drugs, such as human immunodeficiency virus (HIV) and hepatitis C virus (HCV) infection, crime and legal problems, overdose (death) and other morbidity and mortality. METHODS AND RESULTS: The framework was developed collaboratively using consensus methods involving nominal group meetings, review of existing quality standards, repeated email commenting rounds and qualitative analysis of opinions/experiences from a broad range of professionals/experts, including members of civil society and organisations representing people who use drugs. Twelve priority candidate indicators are proposed for opioid agonist therapy (OAT), needle and syringe programmes (NSP) and generic cross-cutting aspects of harm reduction (and potentially other drug) services. Under the specific OAT indicators, priority indicators included 'coverage', 'waiting list time', 'dosage' and 'availability in prisons'. For the specific NSP indicators, the priority indicators included 'coverage', 'number of needles/syringes distributed/collected', 'provision of other drug use paraphernalia' and 'availability in prisons'. Among the generic or cross-cutting indicators the priority indicators were 'infectious diseases counselling and care', 'take away naloxone', 'information on safe use/sex' and 'condoms'. We discuss conditions for the successful development of the suggested indicators and constraints (e.g. funding, ideology). We propose conducting a pilot study to test the feasibility and applicability of the proposed indicators before their scaling up and routine implementation, to evaluate their effectiveness in comparing service coverage and quality across countries. CONCLUSIONS: The establishment of an improved set of validated and internationally agreed upon best practice indicators for monitoring harm reduction service will provide a structural basis for public health and epidemiological studies and support evidence and human rights-based health policies, services and interventions

Auger-electron emission following fast (MeV) molecular- and atomic-ion impact on thin C-foils

Auger electron emission following the excitation of molecular (CO/sub 2//sup +/ and N/sub 2//sup +/) and atomic ions (C/sup +/ and N/sup +/) in thin carbon foils has been measured at MeV impact energies. Relative Auger electron yields from molecular-ion impact have been compared to that from atomic ion impact at equal ion velocities

MOLECULAR MOTIONS IN A VISCOUS ORGANIC LIQUID : FERROCENE IN COLD BUTYL PHTHALATE

Les deux buts principaux de ce travail sont : a) de déterminer si la diffusion de rotation peut être observée en même temps que celle de translation et b) d'éclaircir le fait que augmente lorsqu'on chauffe le verre. Nos résultats montrent que : a) la diffusion moléculaire rotationelle ne s'observera probablement jamais en utilisant la spectroscopie Mössbauer ; b) qu'il existe vraiment une augmentation rapide de au-dessus de Tg. Cette augmentation est liée à un accroissement rapide et linéaire du nombre de modes mous pour le liquide, au-dessus de la température de transition vitreuse.The two main purposes of this work were to learn if : a) rotational diffusion could be seen along with translational, and b) to clarify the gain in as the glass was heated. Our observations show that : a) rotational molecular diffusion is not likely ever to be observed by Mössbauer technique and b) that there is indeed a fast increase in above Tg. This increase is correlated with a rapid and linear increase of the number of soft modes for the liquid above the glass transition temperature

MOTIONS IN A VISCOUS INORGANIC LIQUID : FERROUS ION IN COLD PHOSPHORIC ACID

Le but de ce travail était de décider si : a) il y a des effets de relaxation rotationnels quand la diffusion devient importante au-dessus de la température Tg de la transition vitreuse ; b) on peut expliquer l'absorption Mössbauer dans un modèle de dynamique de solides vitreux et de liquides. Nous montrons qu'on n'observe pas de relaxation rotationnelle, et qu'il y a un accroissement rapide avec la température, à partir de Tg des modes mous, ce qui apparaît à la fois dans les mesures d'effet Mössbauer et de diffusion Raman.The two main purposes of this work were to decide : a) are there rotational relaxation effects when diffusion becomes important above the glass transition temperature Tg ; and b) can the intensity of the MB absorption be understood in terms of glass and liquid dynamics ? We report that rotational relaxation is not seen, and that there is a rapid increase in soft modes with temperature beginning at Tg seen both by Mössbauer technique and by Raman scattering