High-quality ion beams by irradiating a nano-structured target with a petawatt laser pulse

We present a novel laser based ion acceleration scheme, where a petawatt circularly polarized laser pulse is shot on an ultra-thin (nano-scale) double-layer target. Our scheme allows the production of high-quality light ion beams with both energy and angular dispersion controllable by the target properties. We show that extraction of all electrons from the target by radiation pressure can lead to a very effective two step acceleration process for light ions if the target is designed correctly. Relativistic protons should be obtainable with pulse powers of a few petawatt. Careful analytical modeling yields estimates for characteristic beam parameters and requirements on the laser pulse quality, in excellent agreement with one and two-dimensional Particle-in Cell simulations.Comment: 18 pages, 7 figures, accepted in New. J. Phy

Amino acid sequences of proteins from Leptospira serovar pomona.

Abstracts: This report describes a partial amino acid sequences from three putative outer envelope proteins from Leptospira serovar pomona. In order to obtain internal fragments for protein sequencing, enzymatic and chemical digestion was performed. The enzyme clostripain was used to digest the proteins 32 and 45kDa. In situ digestion of 40kDa molecular weight protein was accomplished using cyanogen bromide. The 32kDa protein generated two fragments, one of 21kDa and another of 10kDa that yielded five residues. A fragment of 24 kDa that yielded nineteen residues of amino acids was obtained from 45 kDa protein. A fragment with a molecular weight of 20 kDa, yielding a twenty amino acids sequence from the 40kDa protein

Marked influence of the nature of chemical bond on CP-violating signature in molecular ions HBr+\mathrm{HBr}^{+} and HI+\mathrm{HI}^{+}

Heavy polar molecules offer a great sensitivity to the electron Electric Dipole Moment(EDM). To guide emerging searches for EDMs with molecular ions, we estimate the EDM-induced energy corrections for hydrogen halide ions $\mathrm{HBr}^{+}$ and $\mathrm{HI}^{+}$ in their respective ground $X ^2\Pi_{3/2}$ states. We find that the energy corrections due to EDM for the two ions differ by an unexpectedly large factor of fifteen. We demonstrate that a major part of this enhancement is due to a dissimilarity in the nature of the chemical bond for the two ions: the bond that is nearly of ionic character in $\mathrm{HBr}^{+}$ exhibits predominantly covalent nature in $\mathrm{HI}^{+}$. We conclude that because of this enhancement the HI$^+$ ion may be a potentially competitive candidate for the EDM search.Comment: This manuscript has been accepted for publication in Physical Review Letters. The paper is now being prepared for publicatio

Fourier transform spectroscopy and coupled-channel deperturbation treatment of the A1Sigma+ ~ b3Pi complex of KCs molecule

The laser induced fluorescence (LIF) spectra A1Sigma ~ b3Pi --> X1Sigma+ of KCs dimer were recorded in near infrared region by Fourier Transform Spectrometer with a resolution of 0.03 cm-1. Overall more than 200 LIF spectra were rotationally assigned to 39K133Cs and 41K133Cs isotopomers yielding with the uncertainty of 0.003-0.01 cm-1 more than 3400 rovibronic term values of the strongly mixed singlet A1Sigma+ and triplet b3Pi states. Experimental data massive starts from the lowest vibrational level v_A=0 of the singlet and nonuniformly cover the energy range from 10040 to 13250 cm-1 with rotational quantum numbers J from 7 to 225. Besides of the dominating regular A1Sigma+ ~ b3P Omega=0 interactions the weak and local heterogenous A1S+ ~ b3P Omega=1 perturbations have been discovered and analyzed. Coupled-channel deperturbation analysis of the experimental 39K133Cs e-parity termvalues of the A1S+ ~ b3P complex was accomplished in the framework of the phenomenological 4 x 4 Hamiltonian accounting implicitly for regular interactions with the remote states manifold. The resulting diabatic potential energy curves of the interacting states and relevant spin-orbit coupling matrix elements defined analytically by Expanded Morse Oscillators model reproduce 95% of experimental data field of the 39K133Cs isotopomer with a standard deviation of 0.004 cm-1 which is consistent with the uncertainty of the experiment. Reliability of the derived parameters was additionally confirmed by a good agreement between the predicted and experimental termvalues of 41K133Cs isotopomer. Calculated intensity distributions in the A ~ b --> X LIF progressions are also consistent with their experimental counterparts.Comment: 17 pages, 14 figure

Development and Characterisation of a Gas System and its Associated Slow-Control System for an ATLAS Small-Strip Thin Gap Chamber Testing Facility

A quality assurance and performance qualification laboratory was built at McGill University for the Canadian-made small-strip Thin Gap Chamber (sTGC) muon detectors produced for the 2019-2020 ATLAS experiment muon spectrometer upgrade. The facility uses cosmic rays as a muon source to ionise the quenching gas mixture of pentane and carbon dioxide flowing through the sTGC detector. A gas system was developed and characterised for this purpose, with a simple and efficient gas condenser design utilizing a Peltier thermoelectric cooler (TEC). The gas system was tested to provide the desired 45 vol% pentane concentration. For continuous operations, a state-machine system was implemented with alerting and remote monitoring features to run all cosmic-ray data-acquisition associated slow-control systems, such as high/low voltage, gas system and environmental monitoring, in a safe and continuous mode, even in the absence of an operator.Comment: 23 pages, LaTeX, 14 figures, 4 tables, proof corrections for Journal of Instrumentation (JINST), including corrected Fig. 8b

Relations between Rydberg-valence interactions in the O₂ molecule

Using a single-configuration formulation, analytical expressions are derived for the (X²Πg) nsσg, npπu, and npσu Rydberg-valence interaction matrix elements in O₂. In addition, new results from diabatic, coupled-channel deperturbations of experimental data dependent on these interactions are reported for n=3 and 4. Using these results, the large differences in magnitude between the Rydberg-valence couplings for the constituent states of the npπuRydberg complex that are predicted by the analytical expressions are verified experimentally. Effective values for several two-electron integrals are obtained semiempirically through comparison between analytical expressions and deperturbed experimental values for the Rydberg-state energies and Rydberg-valence couplings, allowing predictions to be made for the spectroscopy of the npπu ¹Σ−uRydberg states which have yet to be observed

High-resolution Fourier-transform XUV photoabsorption spectroscopy of 14N15N

The first comprehensive high-resolution photoabsorption spectrum of 14N15N has been recorded using the Fourier-transform spectrometer attached to the Desirs beamline at the Soleil synchrotron. Observations are made in the extreme ultraviolet (XUV) and span 100,000-109,000 cm-1 (100-91.7 nm). The observed absorption lines have been assigned to 25 bands and reduced to a set of transition energies, f values, and linewidths. This analysis has verified the predictions of a theoretical model of N2 that simulates its photoabsorption and photodissociation cross section by solution of an isotopomer independent formulation of the coupled-channel Schroedinger equation. The mass dependence of predissociation linewidths and oscillator strengths is clearly evident and many local perturbations of transition energies, strengths, and widths within individual rotational series have been observed.Comment: 14 pages, 8 figures, one data archiv

Predissociation mechanism for the lowest ¹Πu states of N₂

Separate coupled-channel Schrödinger-equation (CSE) models of the interacting ¹Πu (b,c,o) and ³Πu (C,C′) states of N₂ are combined, through the inclusion of spin-orbit interactions, to produce a five-channel CSE model of the N₂predissociation. Comparison of the model calculations with an experimental database, consisting principally of detailed new measurements of the vibrational and isotopic dependence of the Πu1linewidths and lifetimes, provides convincing evidence that the predissociation of the lowest ¹Πu levels in N2 is primarily an indirect process, involving spin-orbit coupling between the b¹Πu- and C³Πu-state levels, the latter levels themselves heavily predissociated electrostatically by the C′³Πu continuum. The well-known large width of the b(v=3) level in ¹⁴N₂ is caused by an accidental degeneracy with C(v=9). This CSE model provides the first quantitative explanation of the predissociation mechanism for the dipole-accessible ¹Πu states of N₂, and is thus likely to prove useful in the construction of realistic radiative-transfer and photochemical models for nitrogen-rich planetary atmospheres.This work was partially supported by the Australian Research Council Discovery Program

Northern Ghana hydrogeological assessment project

Groundwater is the most viable source of potable water in northern Ghana, West Africa, especially for the 80% rural inhabitants. Millions of dollars have been expended there on groundwater-based water supply infrastructures, and these expenditures are likely to continue in coming decades. The Hydrogeological Assessment Project (HAP) of the Northern Regions of Ghana was initiated to provide scientific background for groundwater-based supply projects as well as resource management. This paper summarizes the technical approaches and results to date, which include a compilation of available data, targeted field data collection, and the development of a regional hydrogeological synthesis

Social marketing and healthy eating : Findings from young people in Greece

This document is the Accepted Manuscript version. The final publication is available at Springer via http://dx.doi.org/10.1007/s12208-013-0112-xGreece has high rates of obesity and non-communicable diseases owing to poor dietary choices. This research provides lessons for social marketing to tackle the severe nutrition-related problems in this country by obtaining insight into the eating behaviour of young adults aged 18–23. Also, the main behavioural theories used to inform the research are critically discussed. The research was conducted in Athens. Nine focus groups with young adults from eight educational institutions were conducted and fifty-nine participants’ views towards eating habits, healthy eating and the factors that affect their food choices were explored. The study found that the participants adopted unhealthier nutritional habits after enrolment. Motivations for healthy eating were good health, appearance and psychological consequences, while barriers included lack of time, fast-food availability and taste, peer pressure, lack of knowledge and lack of family support. Participants reported lack of supportive environments when deciding on food choices. Based on the findings, recommendations about the development of the basic 4Ps of the marketing mix, as well as of a fifth P, for Policy are proposedPeer reviewe