A single-crystal CVD diamond detector (DD) of a sandwich structure was used for measurement of soft X-rays and ions emitted from plasmas obtained with the use the PALS laser system in Prague. The detector was fabricated in the Institute of Nuclear Physics PAN in Cracow with the use of diamond material obtained from Element Six, Inc. In the laser experiment, the responses of the detector to X-rays and ions were compared to the responses of an ion collector (IC). The signals from the DD proved to be much different to the ones from the IC which is explained by different mechanisms of producing current in both detectors. Due to high sensitivity, the DD is useful for measurement of fast protons. Both detectors can be used for simultaneous measurement of soft X-rays and ions from the same laser shot and the data obtained are complementary.

In this work, we report on the characterization of pulsed soft X-rays emitted from laser-produced plasma by different targets. The measurements were performed in a vacuum stainless-steel chamber at 10-7 mbar .The plasma was generated by a pulsed KrF excimer laser of 248 nm laser wavelength, operating at single shot and having a pulses of 23 ns FWHM. The beam was focused on pure Si, Cu and Ta targets. The laser energies were 40, 80 and 120 mJ, concentrated onto a spot of about 0.01 cm2, with a resulting irradiance of 1.7, 3.5 and 5.2x108 Wcm-2. The utilized detector was a very sensitive Faraday cup which opportunely biased was able to record time resolved signals of X-rays and to estimate their energy. The found X-rays energy values were compared to the ion temperature of the target plasma fitting the time resolved ion current signals by the shifted Maxwell-Boltzmann velocity distribution.

In this paper, we report the successful growth of MgF2 thin films on Si and sapphire (Al2O3) substrates at room temperature by direct laser ablation of a pure MgF2 target. The irradiations were performed at high vacuum (10-5 Pa) using the forth harmonic of a Neodymium-doped Yttrium Aluminum Garnet (Nd:YAG) laser (λ = 266 nm, τFWHM = 7 ns) with energy density of about 10 J/cm2. Uniform films, with a good adhesion on the substrate were obtained. The average ablation and deposition rates resulted to be 1.1 μg/pulse and 0.03 Å/pulse, respectively. Different diagnostic techniques were used to study the morphology and chemical composition of deposited films.

The effects of laser fluence on the morphology of Y films in the regime characteristic of multiple-pulse laser deposition were investigated. Y thin films were deposited on Silicon and Copper substrates. The samples deposited on Silicon substrate were used to deduce the morphology and the thickness of the deposited films. On the contrary, the samples deposited on Copper substrate were tested as photocathodes in a DC photodiode cell. The interest to produce Y-based photocathodes is due to the low work function of this metal with the possibility to drive such photocathodes with a visible radiation in the radio-frequency photo-injector. In this way it is possible to reduce the thermal emittance of the photoelectron beam and to increase the photocurrent intensity by utilizing the second harmonic of Ti:Sa driver laser. The quantum efficiency was measured for the first time by using a visible CW laser diode emitting at 406 nm.

Ions of different elements were generated by laser-induced-plasma and accelerated by a two adjacent cavities. Therefore, the ions were undergone a double acceleration imparting a maximum ion energy of 160 keV per charge state. We analyzed the extracted charge from a Cu target as a function of the accelerating voltage. At 60 kV of total accelerating voltage, the maximum current peak was of 5.3 mA. The ion flux resulted of 3.4x1011 ions/cm2. The normalized emittance measured by pepper pot method at 60 kV was of 0.22 π mm mrad. By this machine, biomedical materials as UHMWPE were implanted with carbon and titanium ions. At a total ion flux of 2x1015 ions/cm2 the polyethylene surface increased its micro hardness of about 3-hold measured by the scratch test. Considering the ion emission cone dimension, we estimated a total extracted charge per pulse of 200 nC.

Pb thin films were prepared by pulsed laser deposition on a Si (100) substrate at different growth temperatures to investigate their morphology and structure. The morphological analysis of the thin metal films showed the formation of spherical submicrometer grains whose average size decreased with temperature. X-ray diffraction measurements confirmed that growth temperature influences the Pb polycrystalline film structure. A preferred orientation of Pb (111) normal to the substrate was achieved at 30° C and became increasingly pronounced along the Pb (200) plane as the substrate temperature increased. These thin films could be used to synthesize innovative materials, such as metallic photocathodes, with improved photoemission performances.

Silver artefacts and particularly ancient silver artefacts present the serious problem of the black look due to ambient contamination. The black colour is the consequence of the layer forming on the surface made of acanthite and jalpaite, both compounds are sulphur composts. Recently UV laser cleaning technique has demonstrated to be very promising in processing of cultural artefacts. To operate on artefacts without to contaminate the bulk, first we determined the laser fluence threshold of the bulk, second we controlled the surface compounds and at the end we operated the laser irradiation. In this work we utilised certified silver and silver/copper samples in order to perform preliminary studies. The threshold fluence we found were 780 and 510 mJ/cm2 for the Ag pure and for the Ag/Cu alloy, respectively. The jalpaite concentration on Ag/Cu sample increased after the laser dose of 25 J/cm2, while for higher laser dose its value lowered pointing out that complex processes take part during the laser application. As a successful of our studies we applied the technique on a Carlino coin made of silver coined in 1689 under King Carlo II. The analyses were performed by two different techniques able to find the percentage of elements and the chemical compounds; the EDXRF and the XRD. We found that the sulphur concentration decreased on laser dose. Operating on the coin up to a dose of 280 J/cm2 the sulphur concentration deceases up to 20 %, while the coin look becomes clear just after a 50 J/cm2.

We review the current status of metallic photocathodes based on thin films prepared by pulsed laser deposition (PLD) and we explore ways to improve the performance of these devices. PLD seems to be a very efficient and suitable technique for producing adherent and uniform thin films. Time-resolved mass spectrometric investigations definitively suggest that the deposition of high-purity metallic thin films should be carried out in ultrahigh vacuum systems and after a deep and careful laser cleaning of the target surface. Moreover, the laser cleaning of the target surface is highly recommended not only to remove the first contaminated layers but also to improve the quality of the vacuum by reducing the partial pressure of reactive chemical species as H2O, H2, and O2 molecules. The challenge to realize high-purity Mg and Y thin films is very interesting for the photocathode R&D due to the good photoemission properties of these metals.

High purity yttrium was ablated by using frequency quadrupled ultra-violet pulses of a Nd:YAG laser (λ=266 nm, τFWHM=7 ns) with power density of about 1 GW/cm2. Laser ablation process was studied using in-situ mass spectrometry of the ablated species in combination with ex-situ analyses of both target surface and deposited films. An increase on the Y ablation rate was found at the beginning, followed by a significant drop with increasing of the number of laser pulses per site until it reaches a constant value after 40 pulses per site. Initial topographic changes on the target surface, observed by scanning electron microscope investigations, and plasma shielding effect could be the origin of these changes on the ablation rate. Careful time-integrated and -resolved mass spectrometric studies of the laser ablated material indicate evident hydridation and oxidation processes in gas phase of ablated yttrium. These results clearly suggest that high purity metallic thin films can be deposited only after a deep and prolonged laser cleaning treatment of the target surface. The present parametric studies are aimed and tailored to prepare photocathodes based on Y thin films to be used in RF photoinjectors.

A new LIS configuration was studied and realized in order to generate and accelerate ions of different elements. This ion source consisted of a laser-induced plasma from solid targets where the plume was made to expand before the action of the accelerating field. The accelerating field was reached by the application of two high voltage power supplies of different polarity. Therefore, the ions were undergone to double acceleration which can imprint a maximum ion energy up to 160keV per charge state. We analyzed the extracted charge from a Cu target as a function of the accelerating voltage at the laser fluence of 1.7 and 2.3 J/cm^2. At 60kV of total accelerating voltage and higher laser fluence, the maximum ion dose was of 10^12 ions/cm^2. Under this last conditions the maximum output current was 5 mA and the emittance measured by pepper pot method resulted of 0.22 π mm mrad. By this machine biomedical materials as UHMWPE were implanted with carbon and titanium ions. At doses of 6x10^15 ions/cm^2 the polyethylene surface increased its micro hardness of about 3-hold measured by the scratch test.

The properties of pulse laser ablation of Cu and Cu98/Be2 materials are studied and the differences in emission of Cu ions are emphasized. The iodine high-power laser system PALS and a KrF laser were used to perform the experiments at the fundamental harmonics λ = 1.315 µm and  = 248 nm delivering energy up to 500 J and 600 mJ, respectively. Pure Cu and Cu98/Be2 alloy targets of 50 µm, 500 µm and 1000 µm in thickness were ablated to measure the influence of the Be admixture on the emission of Cu ions. The alloy Cu98/Be2 was chosen due to the well defined amount of a beryllium admixture in the plasma in contrary to the incidental amount of carbon, oxygen and hydrogen impurities chemisorbed on target surfaces of Cu and Cu98/Be2 samples. It was approved that the emission of Cu ions driven by the KrF laser exhibits a higher gain from the Cu98/Be2 plasma in contrary to the Cu plasma. The fast ion emission induced by laser intensities near the threshold value is significantly affected by the emission of ionized impurities chemisorbed on the target surface and by repetitive outbursts of fast generated ions. Under these conditions the influence of the 2% Be admixture on the emission of Cu ions plays only a minor role.

We developed an ion accelerator with a double accelerating gap system supplied by two power generators of different polarity.-The ions were generated by laser ion source technique. The laser plasma induced by an excimer KrF laser, freely expanded before the action of accelerating fields. After the first gap action, the ions were again accelerated by a second gap. The total acceleration can imprint a maximum ion energy up to 160 keV per charge state. We analyzed the extracted charge from a Cu target as a function of the accelerating voltage at laser energy of 9, 11 and 17 mJ deposited on a spot of 0.005 cm2. The peak of current density was 3.9, 5.3 mA for the lower and medium laser energy at 60 kV. At the highest laser energy, the maximum output current was 11.7 mA with an accelerating voltage of 50 kV. The maximum ion dose was estimated to be of 1012 ions/cm2. Under the condition of 60 kV accelerating voltage and 5.3 mA output current the normalized emittance of the beam measured by pepper pot method was 0.22 π mm mrad.

In this work, we performed experiments of absorption of hydrogen and deuteriumgas by Pd thin films, and we compared the behavior of these samples to unprocessed films. We also employed a continuous wave He–Ne laser to irradiate the samples inside the chamber during the treatment, in order to increase the gas absorption. Using a scanning electron microscope (SEM) and an electron probe micro-analyzer (EDX), we observed structures like spots on the surface of the treated samples. Inside the spots, elements other than Pd were found. Based on these results, we determined that gas loading is an effective way to transmute elements, and the laser action has been a very effective way to increase morphological changes in the treated samples.

In this work two different techniques to modify the polymeric surfaces are compared; Laser irradiation and ion implantation were performed on Ultra High Molecular Weight Polyethylene (UHMWPE) samples. The irradiation treatment was performed by using two different laser sources operating in the UV and IR range, applying many laser shots in air atmosphere on the polymer surface. Ion implantation was performed using a new LIS (Laser Ion Source) accelerator with an accelerating voltage of 40 kV. Contact angle, roughness and Fourier Transform Infra Red (FT-IR) measurements were performed on the samples before and after the two treatments in order to obtain information on the UHMWPE modification.

We study the velocity distribution of ions delivered by plasma whihs is induced by UV Laser.

We report a design of photocathode, which combines the good photoemissive properties of lead (Pb) and the advantages of superconducting performance of niobium (Nb) when installed into a superconducting radio-frequency gun. The new configuration is obtained by a coating of Nb thin film grown on a disk of Pb via pulsed laser deposition. The central emitting area of Pb is masked by a shield to avoid the Nb deposition. The nanomechanical properties of the Nb film, obtained through nanoindentation measurements, reveal a hardness of 2.8±0.3 GPa, while the study of the electrical resistivity of the film shows the appearance of the superconducting transitions at 9.3 K and 7.3 K for Nb and Pb, respectively, very close to the bulk material values. Additionally, morphological, structural and contamination studies of Nb thin film expose a very low droplet density on the substrate surface, a small polycrystalline orientation of the films and a low contamination level. These results, together with the acceptable Pb quantum efficiency of 2×10−5 found at 266 nm, demonstrate the potentiality of the new concept photocathode.

We propose a new photocathode configuration which presents the quantum efficiency and work function of yttrium (Y) and at the same time preserves all of the advantages of copper (Cu) when inserted into a radio-frequency gun. The configuration consists of a disk of Y covered by a coating of Cu deposited using the pulsed laser ablation technique, while masking the central part of the Y disk by a shield making the photoemission directly from the Y bulk possible. The new device was characterised by scanning electron microscopy to deduce the morphology and by X-ray diffraction to obtain structure information on both Cu film and Y substrate. The electrical resistivity of the Cu film was also measured obtaining a value slightly greater than that of bulk high purity

Time-of-flight spectra of C, Fe, and Si ions produced with the use of a KrF excimer laser have been analyzed. Ion currents were collected by Faraday cups and their responses were analyzed using a detector signal function. This function was derived from shifted Maxwell-Boltzmann velocity distribution, in order to uncover the contribution of partial currents of all the ionized species constituting the expanding plasma plume. The deconvolution method allowed to estimate parameters of the plasma, such as the ion temperature and the center-of-mass velocities of expanding ionized species. Furthermore, the linear charge-state dependence of the center-of-mass velocity has revealed the contribution of hydrodynamic and electrostatic forces to the expansion velocity of the plasma. The nearly isotropic distribution of the center-of-mass velocity indicates

We demonstrate that chemical reactions leading to the formation of AlO radicals in plasmas produced by ablation of aluminum or Ti-sapphire with ultraviolet nanosecond laser pulses can be predicted by the model of local thermodynamic equilibrium. Therefore, emission spectra recorded with an echelle spectrometer and a gated detector were compared to the spectral radiance computed for uniform and nonuniform equilibrium plasmas. The calculations are based on analytical solutions of the radiation transfer equation. The simulations show that the plasmas produced in argon background gas are almost uniform, whereas temperature and density gradients are evidenced in air. Furthermore, chemical reactions exclusively occur in the cold plume periphery for ablation in air. The formation of AlO is negligible in argon as the plasma temperature is too large in the time interval of interest up to several microseconds. Finally, the validity of local thermodynamic equilibrium is shown to depend on time, space, and on the elemental composition. The presented conclusions are of interest for material analysis via laser-induced breakdown spectroscopy and for laser materials processing.

Plasmas induced by UV laser ablation have been studied and analysed using timeof- flight measurements. A KrF laser beam of 23 ns FWHM time duration was focused into Si and Nb targets with a moderate laser fluence of 2 J/cm2. A suitable theoretical expressions were derived for fitting the recorded ion current under the assumption of a “shifted” Maxwell- Boltzmann velocity distribution. The deconvolution of time resolved ion current signals, taking into account a multi-mode velocity distribution has revealed that the contribution of the different charge states of ions in the plasma induces electric field which accelerate the expanding plasma along the target normal.

In this work, the deposition of Y thin films by laser beams with 0.5 ps and 5 ps pulse durations at different laser fluences (1.2-6.4 J/cm(2)) is reported. The morphology of the deposited films and of the ablated target surface is investigated by scanning electron microscopy analyses. The present results show that the films, well adherent to the substrates, are characterized by a high abundance of sub-micrometric particulates with average size less than 0.3 mu m, whose density decreases with increasing laser fluence. The formation of columnar structures observed on the target surface seems to be responsible of the poor film homogeneity. Acceptable deposition rate in the range of 0.08-0.16 A/pulse with 5 ps pulse duration is found; on the contrary with 0.5 ps pulse duration, it is not possible to get information on deposition rate as a function of the laser fluence due to the high non-uniformity of the films. A comparison with the results previously obtained in ns regime is presented and discussed. The achievements of our investigation will be useful to optimize the synthesis of photocathodes based on Y films for the production of bright electron beams in radio-frequency photoinjectors.

Nanoparticles of ZnO and Zn1−xMnxO were synthesized by pulsed laser ablation in liquid medium (PLAL). Metal zinc target was used for preparing of pure ZnO nanostructures and Zn1−xMnxO ceramic plates served for preparing of ternary nanoparticles. As synthesized nanomaterials are characterized using scanning electron microscopy (SEM), energy dispersive spectroscopy analysis (EDS), atomic force microscopy (AFM), UV-vis absorption, photoluminescence and Faraday rotation spectroscopy. SEM images showed a well-defined flower-like nanostructures. Absorption edge of Zn0.95Mn0.05O nanoparticles in colloid solution exhibits blue shift due to confinement effect. The observed photoluminescence peaks are attributed to the band-edge transitions and vacancies or defects. The Faraday rotation as a function of photon energy demonstrates behavior typical for diluted magnetic semiconductors (DMSs) in paramagnetic state.