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Synopsis Wigner time delay in photodetachment of Br− has been studied. The absence of Coulomb phase in photodetachment process makes the Wigner time delay more sensitive to the centrifugal barrier shape resonance and threshold effects. Important relativistic effects have been found near the threshold region.

The 30th International Conference on Photonic, Electronic and Atomic Collisions (XXX ICPEAC) was held at the Cairns Convention Centre, Queensland, Australia on 26 July - 1 August, 2017, organized by the Australian National University (ANU, Canberra), Curtin University (Perth, Western Australia) and Griffith University (Queensland). Held biannually, ICPEAC is one of the largest conferences on the atomic and molecular physics calendar, and covers the recent progress in photonic, electronic, and atomic collisions with matter. With a history dating back to 1958, the ICPEAC has its second coming to the Sunshine State of Queensland, the first of which being the 1991 Australian ICPEAC in Brisbane. With the selection of Cairns as the venue for the ICPEAC XXX the local organizers began their preparations six years ahead in anticipation of the event.The conference brought together 500 participants from 50 countries and attracted 680 contributed papers for presentation in poster sessions. Among the latter, 311 are presented in issues 2-12 of this volume of the Journal of Physics Conference Series. In addition, five plenary lectures by Linda Young, Clifford Surko, Henrik Cederquist, Tilman Pfau and Reinhard Kienberger have been presented along with 62 progress reports and 26 special reports. The latter "hot topics" were selected by the ICPEAC Program Committee from the contributed papers. Detailed write-ups of most of the invited lectures and reports are presented in issue 1 of this volume, constituting a comprehensive and tangible record of the meeting.Preceeding the conference, three distinguished scientists: Barry Schneider (NIST, USA), Chris Greene (Purdue University, USA) and Thomas Pfeifer (Max-Plank Institute, Germany) presented their tutorial lectures specifically designed for students and early career researchers.During the conference, the 2017 IUPAP Young Scientist Prize was awarded to Johannes Feist (Universidad Autonoma de Madrid, Spain). The Sheldon Datz Prize for an Outstanding Young Scientist Attending ICPEAC was awarded to Dermot Green (Queen's University Belfast, UK).The Local Organizing Committee would like to express its gratitude to Tourism and Events Queensland (TEQ), the International Union for Pure and Applied Physics (IUPAP), all the conference sponsors for their financial support. With particular emphasis we thank the group of volunteers from the ANU and Curtin University for their efforts in orchestrating the event.Finally, the Local Organizing Committee would like to thank all the ICPEAC participants for their support and contributions to the conference.The Editors,Alexander Bray, Sean Hodgman, Joshua Machacek, Anatoli Kheifets(Australian National University, Canberra, Australia)

We present the results of attosecond angular streaking of atomic Hydrogen using elliptically polarized, 5.5 fs pulses that are centered around 770 nm, within the intensity range of 1.65 to 4 × 1014 W/cm2. We measure angular offsets in the photo-electron momentum distribution relative to the peak of the electric field of light in the polarization plane. We find a strong agreement in these results with the solutions of complete 3D-TDSE simulations. Further, we compute the contribution of coulomb effects (between the ionized electron-parent ion) to the measured angular offsets using Yukawa potential, subtracting which yields the real 'tunneling delays'.

Transverse electron momentum distribution (TEMD) of the spin-orbit wave packets launched in a pump-probe sequential double ionization from the valence shell of Ar is calculated by solving the time-dependent Schrodinger equation (TDSE). Results are compared with a simple tunneling formula and recent measurements.

Wigner time delay has been studied in the shape resonance region for the outer nd→ef photoionization transitions in atomic Zn and Cd.

We present the results of an investigation of the measurement of the transverse electron momentum (TEMD) distribution of atoms ionized though the interaction of strong-field light pulses of varying ellipticity. We show though experiment and theory that the TEMD for the tunneling regime and the over-the-barrier regime (OB) evolves in a qualitatively different way when polarization state of the ionizing laser changes ellipticity.

Wigner time delay for inner and outer shells of Ne@C60-5 have been studied using relativistic random phase approximation (RRPA) [1]. Coulomb confinement resonances (CCR) due to the charged nature of fullerene cause prominent effects on the photoionization time delay of 1s subshell. These CCRs in 1s also results in significant modifications of the time delay in 2s and 2p ionization channels through interchannel coupling at energies far above their thresholds.

Time delay in photoionization of a half-filled shell atom is predicted to be strongly term-dependent and subject to the dramatic impact of a giant autoionization resonance. Photoionization of the Mn atom is chosen as a case study.

We study transverse electron momentum distribution (TEMD) in strong field atomic ionization driven by laser pulses with varying ellipticity. We show, that the TEMD in the tunneling and over the barrier ionization regimes evolves in a qualitatively different way when the ellipticity parameter describing polarization state of the driving laser pulse increases.

Time delay in quadrupole (E2) channels is studied in atomic Hg using the Relativistic Random Phase Approximation. Interchannel coupling is found to be extremely important and large time delays are found in the region of quadrupole (E2) Cooper minima.

We analyze a transfer ionization (TI) reaction in the fast proton-helium collision H+ + He → H0 + He2+ + e- by solving a time-dependent Schrodinger equation (TDSE) under the classical projectile motion approximation in one-dimensional kinematics. By comparing results of the TDSE and various perturbative Born series calculations, we conclude that the recent discrepancies of experimental and theoretical data may be attributed to deficiency of the Born models used by other authors. We demonstrate that the correct Born series for TI should include the momentum space overlap between the double ionization amplitude and the wave function of the transferred electron.

In a kinematically complete experiment we have measured the photo double ionization of Helium at a photon energy of 800 eV and observed He2+ ions with 0 momentum, corresponding to a back-to-back-emission of the two electrons. The results are in good agreement with theoretical calculations.

We study time delay in atomic photoionization by circularly polarized light. By considering the Li atom in an excited $2p$ state, we demonstrate a strong time-delay asymmetry between the photoemission of the target electrons that are co- and counter-rotating with the electromagnetic field in the polarization plane. In addition, we observe the time-delay sensitivity to the polar angle of the photoelectron emission in the polarization plane. This modulation depends on the shape and duration of the electromagnetic pulse.

Differential studies on two and three-photon double ionization (DI) of atomic lithium have been performed for photon energies of 50 eV and 59 eV at I ? 5 ? 1013 W/cm2. At 50 eV DI proceeds via the simultaneous absorption of two photons resulting in the correlated emission of two electrons. In contrast for a photon energy of 59 eV, the resonant one photon transition (1s ? 2p) is followed by DI through a second photon. Additionally a competing sequential three photon reaction is observed for both energies. The experimental data is compared with results from non-perturbative close-coupling calculations.

We perform a systematic investigation of the photoelectron group delay in valence shell single ionization of Ne, Ar, Kr and Xe from their respective thresholds to photon energy of 200 eV. This allows us to highlight various important aspects of fundamental atomic physics that can be probed by attosecond time delay measurements and to address several controversies in recent experiments. We also use these data as an input to the time delay calculations of single-photon double ionization (PDI) of noble gas atoms. Various PDI channels are examined and estimates are given for associated time delays due to the shake-off and knock-out processes. These estimates are used to interpret recent measurements of PDI of Xe on the atto-second time scale.

We analyze a time delay of one- and two-electron photoemission from an atom after absorption of an attosecond XUV pulse. We establish this delay by solving the time dependent Schrodinger equation and by subsequent tracing of the field-free evolution of the photoelectron wave packet. This delay can also be related to the energy derivative of the phase of the complex photoionization amplitude which makes the time delay a sensitive probe of many-electron correlation.

We apply a pump-probe approach to study the process of single-photon two-electron ionization of the helium atom. We demonstrate that this approach provides a complete characterization of the double photoionization process, allowing one to reconstruct both the magnitude and phase of the ionization amplitudes.

The interaction of intense few-cycle light pulses and matter has given rise to a number of high-field physical processes that are of great interest. The high non-linearity of such interactions necessitates complex numerical simulations in order to retrieve useful physical measurements from the experimental data. Here we demonstrate quantitative agreement at the 10% level between experimentally obtained integrated photoelectron spectra and numerical simulations for above-threshold ionization in the intense few-cycle regime. The use of atomic hydrogen provides a key experimental innovation as it is the only electronic system for which ab initio simulations in this regime are available.

We apply the convergent close-coupling (CCC) and time-dependent close- coupling (TDCC) methods to describe energy and angular resolved double photoionization (DPI) of lithium at arbitrary energy sharing. By doing so, we are able to evaluate the recoil ion momentum distribution of DPI of Li and make a comparison with recent measurements of Zhu et al. [Phys. Rev. Lett. 103, 103008 (2009)].

We shall consider various aspects of electron-impact ionisation of atoms. Firstly, the recent progress in the formulation of the problem will be outlined. Then application of the convergent close-coupling (CCC) method to the calculation of the total ionisation spin asymmetries will be described for a range of neutral through to highly charged targets. We shall also consider the importance of electron spin in the problem of single and double photoionisation of lithium. Lastly, application of the CCC method to 64.6 eV e-He ionisation fully differential cross sections for in- and out-of-plane geometries will be considered.

A systematic study of multi-photon ionization (MPI) of atomic lithium in ultra-short and intense near-infrared laser pulses has been conducted both experimentally and theoretically. The cross section was measured for intensities spanning across the transition from MPI to over-the-barrier ionization (OBI). It turns out that this transition manifests itself in a substantial change in the photo-electron angular distributions. In a second study pump-probe experiments exciting bound wave packets and probing their time evolution by ionization were performed.

We analyze the recoil-to-binary peak ratio in an energetic (e,2e) reaction on the valence ns sub-shell of noble gas atoms. Dramatic qualitative change in this ratio dependence on the ejected electron energy can be explained by variation of reflectivity of the short-range Hartree-Fock potential. The reflectivity increases profoundly from lighter (He) to heavier (Ne and Ar) noble gas atoms because of modification of the scattering phases due to occupation of the target p orbitals (Levinson theorem). This effect is further modified due to strong inter-shell correlations in Ar. These theoretical predictions are confirmed experimentally.

We report new coplanar (e,2e) measurements characterised by large energy transfer and close to minimum momentum transfer from the projectile to the target. Ionisation of the two-electron targets He and H2 is investigated under these particular kinematics. The experimental data are compared with the predictions of the most elaborate theoretical models. The obtained good agreement motivated us to extend our research to the case of more complex targets such as Ar. Comparison with the most elaborate models in the case of multi-electron targets is excellent. Destructive and constructive interference effects in the case of H2 are observed and discussed.

We review recent applications of the convergent close-coupling (CCC) method to studies of two-photon double ionization (TPDI) of He. In a weak-field regime, the electron-photon interaction can be treated within the lowest order perturbation theory (LOPT) whereas the electron-electron interaction is included in full. The intermediate states of the target can either be represented by a discrete set of B-splines in a box or summed over with an average weight (closure approximation). In a non-perturbative regime, we solve the time-dependent Schr?dinger equation on a square-integrable basis and project this solution on a set of CCC final states. In both regimes, we are able to calculate reliably the total intgrated and full differential TPDI cross-sections. Besides purely numerical results, we introduce a convenient analytical parametrization of the TPDI amplitude in the manner similar to single photon double ionization. Aided with this parametrization, we observe two distinctly different modes of correlated motion of the photoelectron pair. We also derive the angular anisotropy parameters and the recoil ion momentum distribution for TPDI of He. The latter can be compared with recent experimental observations.