Comparison of quantum mechanical and classical trajectory calculations of cross sections for ion-atom impact ionization of negative - and positive -ions for heavy ion fusion applications

Stripping cross sections in nitrogen have been calculated using the classical trajectory approximation and the Born approximation of quantum mechanics for the outer shell electrons of 3.2GeV I$^{-}$ and Cs$^{+}$ ions. A large difference in cross section, up to a factor of six, calculated in quantum mechanics and classical mechanics, has been obtained. Because at such high velocities the Born approximation is well validated, the classical trajectory approach fails to correctly predict the stripping cross sections at high energies for electron orbitals with low ionization potential.Comment: submitted to Phys. Rev.

Post-acute COVID-19 neuropsychiatric symptoms are not associated with ongoing nervous system injury

A proportion of patients infected with severe acute respiratory syndrome coronavirus 2 experience a range of neuropsychiatric symptoms months after infection, including cognitive deficits, depression and anxiety. The mechanisms underpinning such symptoms remain elusive. Recent research has demonstrated that nervous system injury can occur during COVID-19. Whether ongoing neural injury in the months after COVID-19 accounts for the ongoing or emergent neuropsychiatric symptoms is unclear. Within a large prospective cohort study of adult survivors who were hospitalized for severe acute respiratory syndrome coronavirus 2 infection, we analysed plasma markers of nervous system injury and astrocytic activation, measured 6 months post-infection: neurofilament light, glial fibrillary acidic protein and total tau protein. We assessed whether these markers were associated with the severity of the acute COVID-19 illness and with post-acute neuropsychiatric symptoms (as measured by the Patient Health Questionnaire for depression, the General Anxiety Disorder assessment for anxiety, the Montreal Cognitive Assessment for objective cognitive deficit and the cognitive items of the Patient Symptom Questionnaire for subjective cognitive deficit) at 6 months and 1 year post-hospital discharge from COVID-19. No robust associations were found between markers of nervous system injury and severity of acute COVID-19 (except for an association of small effect size between duration of admission and neurofilament light) nor with post-acute neuropsychiatric symptoms. These results suggest that ongoing neuropsychiatric symptoms are not due to ongoing neural injury

Scientific objectives and key features of a sequence of heavy-ion-beam-driven facilities for high energy density physics and fusion

Successful longitudinal and radial compression of intense neutralized heavy ion beams in the Neutralized Drift Compression Experiment (NDCX-I), together with novel acceleration and compression waveforms using existing induction accelerator modules will lead to an upgraded facility (NDCX-II) capable of driving warm dense matter targets to 1 Mbar, and planar direct drive targets to study hydro-coupling efficiency with beams ramping up in velocity and range. Two further significant enhancements in the heavy ion program, construction of IB-HEDPX with more existing accelerator modules, and commencement of design and R&D for a Heavy Ion Driven Target Implosion Experiment (HIDDIX), could occur after successful experiments in NDCX-II, and after successful ignition in NIF, respectively. Fruition of these research opportunities for heavy-ion-driven high energy density physics (HEDP) and fusion over the next twenty years could establish the HEDP target physics knowledge base needed for a heavy ion fusion test facility, as well as for fundamental HEDP in warm dense matter important to many scientific applications as well as to fusion

Scientific objectives and key features of a sequence of heavy-ion-beam-driven facilities for high energy density physics and fusion

Successful longitudinal and radial compression of intense neutralized heavy ion beams in the Neutralized Drift Compression Experiment (NDCX-I), together with novel acceleration and compression waveforms using existing induction accelerator modules will lead to an upgraded facility (NDCX-II) capable of driving warm dense matter targets to 1 Mbar, and planar direct drive targets to study hydro-coupling efficiency with beams ramping up in velocity and range. Two further significant enhancements in the heavy ion program, construction of IB-HEDPX with more existing accelerator modules, and commencement of design and R&D for a Heavy Ion Driven Target Implosion Experiment (HIDDIX), could occur after successful experiments in NDCX-II, and after successful ignition in NIF, respectively. Fruition of these research opportunities for heavy-ion-driven high energy density physics (HEDP) and fusion over the next twenty years could establish the HEDP target physics knowledge base needed for a heavy ion fusion test facility, as well as for fundamental HEDP in warm dense matter important to many scientific applications as well as to fusion