Laser generation of Au ions with charge states above 50+.

Results of recent studies on highly charged Au ion generation, using the intense long pulses of the PALS high power iodine laser (lambda=1.315 microm, E(L)=800 J400 ps), operating under variable experimental conditions (1omega, 3omega, varying target thickness and changing focus positions), are presented. Both the ion collectors and the ion electrostatic analyzers were applied for the identification of ions in a large distance from the target. The time-of-flight collector signals were treated by a means of peak deconvolution assuming a shifted Maxwell-Boltzmann form of the constituent ion current peaks. Attention was paid to the influence of pulse precursor, which becomes evident, especially, if using thinner targets and 1omega. The results for 3omega point to the presence of several groups of ions with the highest recorded charge state Au(53+).

Unintended "incidental" durotomy during surgery of the lumbar spine: medicolegal implications.

A review of 146 medical malpractice cases involving surgery of the lumbar spine disclosed that unintended "incidental" durotomy (23 cases) was the second most frequently named occurrence. In each instance there was an associated alleged complication or sequelae. There appears to be a subset of patients in whom an unintended "incidental" durotomy is associated with perioperative morbidity and long-term sequelae. Considering the frequency with which a dural tear is listed as one of the complaints in medical malpractice cases involving surgery of the lumbar spine, it cannot be considered an entirely "benign event."

Vascular and visceral injuries associated with lumbar disc surgery: medicolegal implications.

Symptomatic perforation of the anterior annulus fibrosus/anterior longitudinal ligament during surgery for herniated lumbar disc disease is one of the more solemn and sobering complications experienced by neurosurgeons or orthopedic surgeons. This complication frequently results in the death of the patient. Its occurrence is probably more common than the medical community would expect. The authors report 21 cases since 1985 in which an injury to an intra-abdominal vessel or viscera occurred. In all cases litigation resulted and a settlement or verdict was rendered. A review of the literature is presented and the medicolegal implications of symptomatic ventral perforations of the annulus fibrosus/anterior longitudinal ligament are discussed.

Proton emission from thin hydrogenated targets irradiated by laser pulses at 10(16) W∕cm2.

The iodine laser at PALS Laboratory in Prague, operating at 1315 nm fundamental harmonics and at 300 ps FWHM pulse length, is employed to irradiate thin hydrogenated targets placed in vacuum at intensities on the order of 10(16) W∕cm(2). The laser-generated plasma is investigated in terms of proton and ion emission in the forward and backward directions. The time-of-flight technique, using ion collectors and semiconductor detectors, is used to measure the ion currents and the corresponding velocities and energies. Thomson parabola spectrometer is employed to separate the contribution of the ion emission from single laser shots. A particular attention is given to the proton production in terms of the maximum energy, emission yield, and angular distribution as a function of the laser energy, focal position, target thickness, and composition. Metallic and polymeric targets allow to generate protons with large energy range and different yield, depending on the laser, target composition, and target geometry properties.

New methods for high current fast ion beam production by laser-driven acceleration.

An overview of the last experimental campaigns on laser-driven ion acceleration performed at the PALS facility in Prague is given. Both the 2 TW, sub-nanosecond iodine laser system and the 20 TW, femtosecond Ti:sapphire laser, recently installed at PALS, are used along our experiments performed in the intensity range 10(16)-10(19) W∕cm(2). The main goal of our studies was to generate high energy, high current ion streams at relatively low laser intensities. The discussed experimental investigations show promising results in terms of maximum ion energy and current density, which make the laser-accelerated ion beams a candidate for new-generation ion sources to be employed in medicine, nuclear physics, matter physics, and industry.

Generation of high currents of carbon ions with the use of subnanosecond near-infrared laser pulses.

Emission of carbon currents reaching values up to 2 A/cm(2) at a distance of 1 m from the laser ion source driven by the subnanosecond Prague Asterix Laser System operated at a fundamental wavelength of 1315 nm is reported. Graphite targets were exposed to intensities up to 5x10(16) W/cm(2) varying both the laser energy and the position of the laser beam focus with respect to the target surface. The maximum energy gain of carbon ions was approximately = 1 MeV/u. At high laser intensities the shape of time-of-flight spectra is also formed by plasma outbursts, whose growth correlates with the oscillatory self-focusing of the laser beam.

Measurements of the highest acceleration gradient for ions produced with a long laser pulse.

Ultrafast plasma light ion streams have been produced using the 300 ps, kJ-class iodine laser, operating at PALS Centre in Prague. Ion detection was performed through standard ion collectors (IC) in time-of-flight configuration (TOF), shielded by thin metallic absorbers. This new diagnostics technique has been theoretically studied and experimentally tested in order to cut the long photopeak contribution and to analyze the ultrafast particle signal. Processing the obtained experimental IC-TOF data, including deconvolution processes of the TOF signals, UV/soft-x-ray photopeak absorption, and ion transmission calculations for different metallic filters, is shown. Mainly amorphous carbon (graphite) targets have been irradiated in order to limit the maximum number of ion charge states and to focus our study on demonstrating the validity of the proposed investigation technique. Maximum ion energy and acceleration gradient estimations as a function of the laser energy and focal spot diameter are reported.