Short Soft X-Ray Sources

EnWe report on the characterization of pulsed soft X-rays emitted from laser-produced plasma. The plasma was generated by 40, 80 and 120 mJ laser energies provided by a pulsed KrF excimer laser focused on pure Si, Cu and Ta targets. 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 with the ion temperature of the plasma obtained by fitting the time resolved ion current signals with a shifted Maxwell-Boltzmann velocity distribution. The results showed that the laser produced Ta plasma induced bunch of X-rays having in average the highest energy values and it was also characterized by ion temperature higher than the ones of the laser produced Si and Cu plasmas

Categorical and dimensional approaches in the evaluation of the relationship between attachment and personality disorders: An empirical study

Although several studies have highlighted the relationship between attachment states of mind and personality disorders (PD), their findings have not been consistent, possibly due to the application of the traditional taxonomic classification model of attachment. A more recently developed dimensional classification of attachment representations, including more specific aspects of trauma-related representations, may have advantages. In this study we compare specific associations and predictive power of the categorical attachment and dimensional models applied to 230 Adult Attachment Interview transcripts obtained from personality disordered and non-psychiatric subjects. We also investigate the role that current levels of psychiatric distress may have in the prediction of PD. The results showed that both models predict the presence of PD, with the dimensional approach doing better in discriminating overall diagnosis of PD. However, both models are less helpful in discriminating specific PD diagnostic subtypes. Current psychiatric distress was found to be the most consistent predictor of PD capturing a large share of the variance and obscuring the role played by attachment variables. The results suggest that attachment parameters correlate with the presence of PD alone and has no specific associations with particular PD subtypes when current psychiatric distress is taken into account

Production and Extraction of Protons by Solid Hydrogenated Targets via UV Laser Ablation

In this work we present the preliminary investigations about the production of proton beams by pulsed laser ablation of solid disks produced by compressed Titanium dihydride powder. The laser we used was an excimer KrF, operating at low intensity and ns pulse duration. The ion emission was analyzed by the time-of-flight technique using a Faraday cup as ion collector. We performed studies on the produced plasma for different laser fluence values and accelerating voltage. In free expansion mode we obtained protons and titanium ions having kinetic energy of some hundred of eV; by applying a postaccelerating voltage we obtained beams up to 15 keV

Determination of recombination length of a non-equilibrium plasma produced by laser ablation

An experimental study of the laser ablation produced plasma evolution is necessary for its deeper understanding, since plasma expansion has both spatially and temporally varying characteristics. We irradiated a Cu target with a KrF laser beam. A small Faraday cup array and an axial Faraday cup were used as diagnostic systems, in order to study the spatial variation in the total charge carried by plasma ions. Charge loss during the plasma expansion was observed, which was attributed to the charged species recombination. This occurred upstream to the critical distance where the plasma density is high enough. Downstream the critical distance the plasma particles collisions were negligible and the ion charge remained frozen. In these experiments it was observed that the critical distance for charge recombination was a function of laser fluence

Application of XeCl308nm excimer laser radiation to mutate industrial microorganisms

EnIn this study, we have investigated the effects of an XeCl308 nm excimer laser radiation on bacterial mutagenesis. Our experiments have revealed that the mutagenesis inducted by the XeCl308 nm excimer laser radiation is independent from RecA protein, the regulator of the SOS response, unlike UV254 nm radiation that is not mutagenic for Escherichia coli mutants lacking the RecA protein. This found suggests that the UV308 nm laser radiation might be mutagenic also in microorganisms naturally lacking the SOS response. To test this hypothesis, we applied our innovative mutagenesis approach on Nonomuraea ATCC 39727, an industrial strain producing an antibiotic, which is relatively refractory to UV254 nm radiation-induced mutagenesis. Our results demonstrated the efficiency of XeCl308 nm excimer laser radiation to induce mutagenesis in Nonomuraea ATCC 39727

Effects of physical stresses on radish seed germination and growth

In this work we explore the consequences on variable magnetic fields applied to radish seeds (Raphanus sativum L.) on germination and seedling growth. Three, different alternate magnetic fields have been tested having a high intensity, 40 mT, at very low frequency, 0.2 Hz (B0.2), a low intensity, 577 µT, at low frequency, 370 kHz (B370), and a very low intensity, about 250 nT, at ultra high frequency, 900 MHz (RF900). These last generate electromagnetic waves which are nowadays very used for mobile communications. Groups of uniform radish seeds were exposed to alternate magnetic fields at three duration time values: i) 120 h (BO.2/1), 260 h (B0.2/2) and 360 h (B0.2/3) at high intensity and very low frequency, 0.2 Hz; ii) 120 h (B370/1), 260 h (B370/2), 360 h (B370/3) at low intensity and low frequency, 370 kHz; iii) 120 h (RF/1), 260 h (RF/2), 360 h (RF/3) at very low intensity and ultra high frequency, 900 MHz. Furthermore, another group of seeds was treated by laser beams of 248 nm wavelength whose magnetic field is coupled to an electric field. These two fields, by the Planck theory, origin the quantum energy, expresses by photons. Therefore, in the laser-matter interaction photons are absorbed dependent on laser shots. Again, we performed experiments at three duration time values that applied: 30 kshots (KrF/1), 80 kshots (KrF/2) and 135 kshots (KrF/3) at 40 mJcm2/ fluence. The magnetic field and electric field presented by the laser beam are approximatively 250 kVm/ and 850 µT, respectively. All treatments were performed at room temperature. Both untreated seeds and each group of seeds exposed to the physical stresses were transferred in Petri dishes and followed for their germination and seedling growth up to 96 h. The results showed that all physical stresses induced by alternate magnetic fields, radiofrequency and laser radiations did not have effect on seed germination as well as on cell elongation growth of the radish hypocotyls in comparison to control seeds. On the contrary, all physical stresses showed a significate stimulation on root growth

Analysis of the Radish Seed Germination and Growth by Radiofrequency Stresses

In this work we report a study on the behavior of radish seed (Raphanus sativum L.) germination and growth under radiofrequency stresses. Groups of uniform seeds were irradiated at five duration time values of 60, 210, 375, 470 and 830 h at medium frequency of 1 Mhz, (MF/1), (MF/2), (MF/3), (MF/4) and (MF/5), respectively; at very high frequency of 100 Mhz, (VHF/1), (VHF/2) f(VHF/3), (VHF/4) and (VHF/5), respectively; at ultra high frequency of 900Mhz, (UHF/1), (UHF/2), (UHF/3), (UHF/4) and (UHF/5), respectively. The exhibited magnetic field for the three frequencies was of about 240 nT and the associate electric field inside the samples was less than 71 V/m, owing to the electric permittivity exposed sample. Another group of uniform radish seeds, irradiated by static magnetic (SM) field of 80 mT for the same time duration, was used as comparison, whereas untreated ones were used as control. The results showed that all physical stresses induced by magnetic fields did not have effect on seed germination as well as on cell elongation growth of the radish hypocotyls. On the contrary, a stimulating effect was observed on root growth

Electron beams produced by innovative photocathodes based on nanodiamond layers

The investigation of two different photocathodes (PCs) based on nanodiamond (ND) layers, irradiated by a KrF nanosecond excimer laser (wavelength, \ensuremath{\lambda}=248\text{ }\text{ }\mathrm{nm}; photon energy, ${E}_{\mathrm{Ph}}=5\text{ }\text{ }\mathrm{eV}$) is reported. The ND layers were deposited by means of a pulsed spray technique. Specifically, the active layer of each PC consisted of untreated (as-received) and hydrogenated ND particles, 250 nm in size, sprayed on a $p$-doped silicon substrate. The ND-based photocathodes were tested in a vacuum chamber at {10}^{\ensuremath{-}6}\text{ }\text{ }\mathrm{mbar} and compared to a Cu-based one, used as reference. All the photocathodes were irradiated at normal incidence. The quantum efficiency (QE) of the photocathodes was assessed. QE values of the ND-based photocathodes were higher than that of the reference one. In particular, the hydrogenated ND-based PC exhibited the highest QE due to the negative electron affinity that results from the surface terminated by hydrogen. Additionally, the photocathode surface/local temperature and the multiphoton process contribution to the electron emission were studied

A Proton Source via Laser Ablation of Hydrogenated Targets

In this work we present results on the extraction of proton beams from a plasma generated by pulsed laser ablation of solid hydrogenated targets. The laser used was an excimer KrF operating at low irradiances (108–109 W/cm2) and nanosecond pulse duration. The ablated targets were disks obtained by compression of TiH2 powder. The ion emission was analyzed by the time-of-flight technique using a Faraday cup as ion collector. In order to improve the ion yield, an electrostatic extraction system was applied. Studies on the produced plasma for different laser irradiances and accelerating voltages have been performed. The results obtained show that this setup is suitable for a high yield proton source

Bobina di Rogowski lineare

Oggigiorno, lo sviluppo e l'uso di impulsi sempre più veloci richiedono sistemi sofisticati per diagnosticarli. La bobina di Rogowski è un dispositivo ben conosciuto, sviluppato per la diagnostica di impulsi di corrente in sistemi a configurazione cilindrica, infatti è conosciuta anche come toro di Rogowski. Recentemente, stanno avendo sempre più successo esperimenti di radiofrequenza per stimolazioni biofisiche con l'uso di linee di trasmissione piane. Così, è stato necessario sviluppare bobine di Rogowski lineari per rilevare impulsi di corrente in conduttori piatti. Simili sistemi sono anche applicabili agli acceleratori di particelle di struttura lineare. In questo lavoro si analizza una bobina di rogowski lineare e si studia l'influenza della sua resistività come pure quella del nucleo magnetico. Il dispositivo sviluppato è in grado di registrare impulsi lunghi alcune centinaia di ns e con tempi di salita di circa 500 ps. Il coefficiente di attenuazione dipende principalmente dal numero di spire che compongono la bobina e dalle approssimazioni fatte sul campo magnetico, negli esperimenti condotti risulta pari a 1300 A/V