Application of position sensitive PIN diodes in Elastic Backscattering Spectrometry

Elastična raspršenja u stražnje i prednje kutove (eng. Elastic Backscattering Spectrometry (EBS) and Elastic Recoil Detection Analysis (ERDA)) su jedne od najkorištenijih metoda za dubinsko elementarno profiliranje uzoraka, a baziraju se na intrakciji brzih MeV-skih iona s jezgrama atoma mete. Detektori su u ovim metodama tipično postavljeni daleko od mete, čime se pokriva mali prostorni kut i tako reduciraju kinematički efekti. Posljedica malog prostornog kuta pokrivenog energijskim detektorom je dugo vrijeme prikupljanja zadovoljavajuće statistike u spektrima te moguće oštećenje uzorka ionskim snopom. Kako bi se minimizirali spomenuti neželjeni efekti, energijski detektor treba se postaviti blizu analiziranog uzorka, no time kut raspršenja više nije precizno definiran, što utječe na pogoršanje energijske, a samim time i dubinske razlučivosti metode. Jedno od rješenja navedenih problema je zamjena konvencionalnog energijskog detektora pozicijsko osjetljivim, koji uz energiju ima mogućnost bilježiti i poziciju detektiranog iona. U ovom radu istražena je potencijalna primjena 2D pozicijsko osjetljive PIN diode (Hamamatsu S2044) za EBS i ERDA mjerenja u konfiguraciji gdje je detektor smješten jako blizu uzorka. Najprije je napravljena karakterizacija 2D PIN diode (određena energijska (125 keV) i prostorna razlučivost (120 μm)). Nakon toga, koristeći spomenutu diodu izmjereni su energijski spektri za više kombinacija snopova i meta u širokom rasponu kutova raspršenja: raspršenje snopova 16O3+ energije 5:0625 MeV i 16O4+ energije 9 MeV na 10 nm 197Au u stražnje kutove te raspršenje snopa 16O4+ energije 9 MeV na C foliji debljine 20 μg/cm2 i raspršenje 12C3+ energije 10 MeV na istoj foliji u prednje kutove. Za svako od mjerenja, rezultirajući prošireni energijski spektar je suma spektara koji odgovaraju različitim prostornim kutovima i kutovima raspršenja. Upotrebom teorijskih formula za kinematičke faktore i udarne presjeke rutherfordskog i Mottovog raspršenja te poznavanjem energije i kuta raspršenja svih detektiranih iona, napravljena je jednostavna korekcija izmjerenih spektara na dobro definirani prostorni kut i kut raspršenja, čime je širina energijskih spektara svedena na energijsku razlučivost detektora (do na mala odstupanja koja su posljedica nedovoljno dobre geometrijske kalibracije eksperimentalnog postava).Elastic Backscattering Spectrometry (EBS) including Forward Scattering (FS) and Elastic Recoil Detection Analysis (ERDA) are the most commonly used Ion Beam Analysis (IBA) techniques for depth profiling of elements in different types of samples. They are based on the interaction of fast MeV ions with the target atom nuclei. Typically, detectors used in EBS and ERDA are placed far from the target covering small solid angles to reduce kinematic effects. As a result of small detector solid angle, a long collection time is often required to obtain sufficiently good statistics, possibly causing ion beam damaging of the sample. In order to overcome these problems, energy detector could be placed close to the measured sample, causing worsening of energy/depth resolution due to the ill-defined scattering angle. Problem can be reduced by using a 2D position sensitive energy detector which measures, beside the energy, position of the scattered ion. In present work, we have investigated application of the 2D Hamamatsu S2044 PIN diode for EBS and ERDA by placing detector very close to the target covering large solid angle. First, the energy (125 keV) and position resolution (120 μm) of the diode were determined. After that, using the above-mentioned diode energy spectra for different beam-target combinations in the wide range of scattering angles were measured: backscattering of 5:0625 MeV 16O3+ and 9 MeV 16O4+ on 10 nm 197Au target, forward scattering of 9 MeV 16O4+ on 20 μg/cm2 carbon foil and forward scattering of 10 MeV 12C3+ on the same foil. For each measurement, the resulting widened energy spectrum was the sum of the spectra corresponding to different solid and scattering angles. Using theoretical formulas for kinematic factors as well as Rutherford and Mott scattering cross sections, and knowing the energy and scattering angle of all detected ions, a simple correction of measured spectra on well-defined solid and scattering angles was made. With this correction the width of the energy spectra was reduced to the level of detector’s energy resolution (small deviations are consequence of insufficiently good geometric calibration of the experimental setup)

Mikrokogeneracija u virtualnoj elektrani

U radu je najprije dan pregled tehnologija kogeneracije. Opisana su područja primjene i karakteristike pojedinih tehnologija. Napravljena je podjela kogeneracije i dodtano opisana primjena mikrokogeneracijskih postrojenja u kućanstvu. Izvršene su prilagodbe norme VDI4655 te pokazani satni profili za tipične dane za električno i toplinsko opterećenje. Konačno, simuliran je pogon kogeneracije za tri karakteristična dana: ljetni zimski te jesenski

Application of position sensitive PIN diodes in Elastic Backscattering Spectrometry

Elastična raspršenja u stražnje i prednje kutove (eng. Elastic Backscattering Spectrometry (EBS) and Elastic Recoil Detection Analysis (ERDA)) su jedne od najkorištenijih metoda za dubinsko elementarno profiliranje uzoraka, a baziraju se na intrakciji brzih MeV-skih iona s jezgrama atoma mete. Detektori su u ovim metodama tipično postavljeni daleko od mete, čime se pokriva mali prostorni kut i tako reduciraju kinematički efekti. Posljedica malog prostornog kuta pokrivenog energijskim detektorom je dugo vrijeme prikupljanja zadovoljavajuće statistike u spektrima te moguće oštećenje uzorka ionskim snopom. Kako bi se minimizirali spomenuti neželjeni efekti, energijski detektor treba se postaviti blizu analiziranog uzorka, no time kut raspršenja više nije precizno definiran, što utječe na pogoršanje energijske, a samim time i dubinske razlučivosti metode. Jedno od rješenja navedenih problema je zamjena konvencionalnog energijskog detektora pozicijsko osjetljivim, koji uz energiju ima mogućnost bilježiti i poziciju detektiranog iona. U ovom radu istražena je potencijalna primjena 2D pozicijsko osjetljive PIN diode (Hamamatsu S2044) za EBS i ERDA mjerenja u konfiguraciji gdje je detektor smješten jako blizu uzorka. Najprije je napravljena karakterizacija 2D PIN diode (određena energijska (125 keV) i prostorna razlučivost (120 μm)). Nakon toga, koristeći spomenutu diodu izmjereni su energijski spektri za više kombinacija snopova i meta u širokom rasponu kutova raspršenja: raspršenje snopova 16O3+ energije 5:0625 MeV i 16O4+ energije 9 MeV na 10 nm 197Au u stražnje kutove te raspršenje snopa 16O4+ energije 9 MeV na C foliji debljine 20 μg/cm2 i raspršenje 12C3+ energije 10 MeV na istoj foliji u prednje kutove. Za svako od mjerenja, rezultirajući prošireni energijski spektar je suma spektara koji odgovaraju različitim prostornim kutovima i kutovima raspršenja. Upotrebom teorijskih formula za kinematičke faktore i udarne presjeke rutherfordskog i Mottovog raspršenja te poznavanjem energije i kuta raspršenja svih detektiranih iona, napravljena je jednostavna korekcija izmjerenih spektara na dobro definirani prostorni kut i kut raspršenja, čime je širina energijskih spektara svedena na energijsku razlučivost detektora (do na mala odstupanja koja su posljedica nedovoljno dobre geometrijske kalibracije eksperimentalnog postava).Elastic Backscattering Spectrometry (EBS) including Forward Scattering (FS) and Elastic Recoil Detection Analysis (ERDA) are the most commonly used Ion Beam Analysis (IBA) techniques for depth profiling of elements in different types of samples. They are based on the interaction of fast MeV ions with the target atom nuclei. Typically, detectors used in EBS and ERDA are placed far from the target covering small solid angles to reduce kinematic effects. As a result of small detector solid angle, a long collection time is often required to obtain sufficiently good statistics, possibly causing ion beam damaging of the sample. In order to overcome these problems, energy detector could be placed close to the measured sample, causing worsening of energy/depth resolution due to the ill-defined scattering angle. Problem can be reduced by using a 2D position sensitive energy detector which measures, beside the energy, position of the scattered ion. In present work, we have investigated application of the 2D Hamamatsu S2044 PIN diode for EBS and ERDA by placing detector very close to the target covering large solid angle. First, the energy (125 keV) and position resolution (120 μm) of the diode were determined. After that, using the above-mentioned diode energy spectra for different beam-target combinations in the wide range of scattering angles were measured: backscattering of 5:0625 MeV 16O3+ and 9 MeV 16O4+ on 10 nm 197Au target, forward scattering of 9 MeV 16O4+ on 20 μg/cm2 carbon foil and forward scattering of 10 MeV 12C3+ on the same foil. For each measurement, the resulting widened energy spectrum was the sum of the spectra corresponding to different solid and scattering angles. Using theoretical formulas for kinematic factors as well as Rutherford and Mott scattering cross sections, and knowing the energy and scattering angle of all detected ions, a simple correction of measured spectra on well-defined solid and scattering angles was made. With this correction the width of the energy spectra was reduced to the level of detector’s energy resolution (small deviations are consequence of insufficiently good geometric calibration of the experimental setup)

Numerical simulations of hydraulic transients in hydropower plant Jajce II

Hydraulic transients in hydropower plant Jajce II (Bosnia and Herzegovina) were simulated with 1D unsteady pipe flow model. High accuracy of the model was accomplished with the use of non-conservative formulation of an unsteady pipe flow model incorporating a modified instantaneous acceleration-based unsteady friction model and second order flux limited numerical scheme. In order to apply the model, complex dual surge tank geometry needed to be represented with a unified surge tank. The numerical model was validated against the measured data on three simulation scenarios, defined with different turbine discharge reductions. Simulation results show a very good agreement between the computed and measured piezometric heads, both in amplitude and frequency of the oscillation

Dependence of Megaelectron Volt Time-of-Flight Secondary Ion Mass Spectrometry Secondary Molecular Ion Yield from Phthalocyanine Blue on Primary Ion Stopping Power

Time-of-flight secondary ion mass spectrometry (TOF SIMS) is a well-established mass spectrometry technique used for the chemical analysis of both organic and inorganic materials. In the last ten years, many advances have been made to improve the yield of secondary molecular ions, especially those desorbed from the surfaces of organic samples. For this reason, cluster ion beams with kiloelectron volt energies for the excitation were mostly used. Alternatively, single-ion beams with megaelectron volt energies can be applied, as was done in the present work. It is well-known that a secondary molecule/ion yield depends strongly on the primary ion stopping power, but the nature of this dependence is not completely clear. Therefore, in the present work, the secondary ion yield from the phthalocyanine blue (C32H16CuN8, organic pigment) was measured for the various combinations of ion masses, energies, and charge states. Measured values were compared with the existing models for ion sputtering. An increase in the secondary yield with the primary ion energy, electronic stopping, velocity, and charge state was found for different types of primary ions. Although this general behavior is valid for all primary ions, there is no single parameter that can describe the measured results for all primary ions at once

Depth profiling of Cr-ITO dual-layer sample with secondary ion mass spectrometry using MeV ions in the low energy region

This work explores the possibility of depth profiling of inorganic materials with Megaelectron Volt Secondary Ion Mass Spectrometry using low energy primary ions (LE MeV SIMS), specifically 555 keV Cu ²⁺ , while etching the surface with 1 keV Ar ⁺ ions. This is demonstrated on a dual-layer sample consisting of 50 nm Cr layer deposited on 150 nm In2O5Sn (ITO) glass. These materials proved to have sufficient secondary ion yield in previous studies using copper ions with energies of several hundred keV. LE MeV SIMS and keV SIMS depth profiles of Cr-ITO dual-layer are compared and corroborated by atomic force microscopy (AFM) and time-of-flight elastic recoil detection analysis (TOF-ERDA). The results show the potential of LE MeV SIMS depth profiling of inorganic multilayer systems in accelerator facilities equipped with MeV SIMS setup and a fairly simple sputtering source

Novi lokaliteti endemičnih vrsta Aquilegia kitaibelii Schott i Cardaminopsis croatica (Schott, Nyman et Kotschy) Jáv. u Hrvatskoj

New localities of two endemic, rare and floristically interesting species in the north-western Dinaric Mountains in Croatia are reported in the paper. Both species are statutorily strictly protected species in Croatia. Aquilegia kitaibelii Schott, as a rare, endemic species, is included in Appendix II of the Habitats Directive (NATURA 2000 Species) and in the IUCN list as a data deficient (DD) species. New localities of A. kitaibelii were found on Mt Obruč and the central and south sections of Mt Velebit, while new localities of Cardaminopsis croatica (Schott, Nyman et Kotschy) Jáv. were discovered on hills in the Gacka Region and the central section of Mt Velebit. In general, both species grow mainly from fissures on rocks together with other petrophilous plant species. It was also noted that A. kitaibelii grows on screes. In Gacka Region C. croatica grows in thermophilous habitats, that is, on rocks with different exposures, together with thermophilous sub-Mediterranean species and with some mountain species of common beech and silver fir forests. In the central section of Mt Velebit, C. croatica also grows in a thermophilous community of forest rocks as well as in anthropogenic habitats, like the edges of gravel roads. These observations suggest the ecological adaptability of this endemic species.U radu su navedeni novi, do sada neobjavljeni lokaliteti dviju endemičnih i floristički zanimljivih vrsta rasprostranjenih na području sjeverozapadnih Dinarida u Hrvatskoj. Obje vrste su u nas i zakonom strogo zaštićene. Jedna od njih je Kitaibelov pakujac (Aquilegia kitaibelii Schott) koji je kao rijetka, endemična vrsta uvrštena na popis NATURA 2000 vrsta. Nova nalazišta Kitaibelova pakujca zabilježena su na širem području planinske skupine planine Obruč te na srednjem i južnom Velebitu, dok su novi lokaliteti hrvatske gušarke (Cardaminopsis croatica (Schott, Nyman et Kotschy) Jáv.) utvrđeni na području srednjeg Velebita i na padinama brežuljaka regije Gacke. Obje vrste na većini novih nalazišta rastu u pukotinama stijena zajedno s drugim petrofilnim vrstama, a Kitaibelov pakujac zabilježili smo i na točilima. Za hrvatsku gušarku posebno su zanimljiva nalazišta u regiji Gackoj, gdje raste na termofilnim stijenama različitih ekspozicija, u okruženju mješavine termofilnih submediteranskih vrsta i nekih brdskih vrsta bukovo-jelovih šuma. Uz Premužićevu stazu na srednjem Velebitu C. croatica se također pojavljuje u termofilnim zajednicama šumskih stijena. Opaženo je i da, osim stijena, hrvatska gušarka nastanjuje i sekundarna, antropogena staništa, kao što su rubovi šumskih cesta, što ukazuje na ekološku plastičnost ove endemične vrste

An ion beam spot size monitor based on a nano-machined Si photodiode probed by means of the ion beam induced charge technique

In this work the utilization of the Ion Beam Induced Charge (IBIC) technique is explored to assess the resolution a 2 MeV Li + ion microbeam raster scanning a micrometer-sized FIB-machined hollows in a silicon photodiode. The analysis of the maps crossing the FIB machined structures evidenced a drop in charge collection efficiency across the perimeter of the hollows combined with a significant recovery of the signal amplitude at the center of the microstructures, thus forming a micrometer-sized feature which can be exploited to estimate the resolution of the probing beam. The results were interpreted according to numerical simulations based on the Shockley-Ramo-Gunn as originating from a FIB-induced surface space charge density. These results offered additional information with respect to what achievable by a confocal photocurrent microscopy analysis of the same device, due to the significantly shorter focal depth of the latter with respect to the probing ion beam. This study suggests the viability of an effective method to evaluate of the resolution of ion microbeams in processes and experiments, which could be beneficial in emerging fields (deterministic implantation, micro-radiobiology, ion lithography) demanding beam spot sizes below the micrometer scale

Effect of Hydrocortisone on Mortality and Organ Support in Patients With Severe COVID-19: The REMAP-CAP COVID-19 Corticosteroid Domain Randomized Clinical Trial.

Importance: Evidence regarding corticosteroid use for severe coronavirus disease 2019 (COVID-19) is limited. Objective: To determine whether hydrocortisone improves outcome for patients with severe COVID-19. Design, Setting, and Participants: An ongoing adaptive platform trial testing multiple interventions within multiple therapeutic domains, for example, antiviral agents, corticosteroids, or immunoglobulin. Between March 9 and June 17, 2020, 614 adult patients with suspected or confirmed COVID-19 were enrolled and randomized within at least 1 domain following admission to an intensive care unit (ICU) for respiratory or cardiovascular organ support at 121 sites in 8 countries. Of these, 403 were randomized to open-label interventions within the corticosteroid domain. The domain was halted after results from another trial were released. Follow-up ended August 12, 2020. Interventions: The corticosteroid domain randomized participants to a fixed 7-day course of intravenous hydrocortisone (50 mg or 100 mg every 6 hours) (n = 143), a shock-dependent course (50 mg every 6 hours when shock was clinically evident) (n = 152), or no hydrocortisone (n = 108). Main Outcomes and Measures: The primary end point was organ support-free days (days alive and free of ICU-based respiratory or cardiovascular support) within 21 days, where patients who died were assigned -1 day. The primary analysis was a bayesian cumulative logistic model that included all patients enrolled with severe COVID-19, adjusting for age, sex, site, region, time, assignment to interventions within other domains, and domain and intervention eligibility. Superiority was defined as the posterior probability of an odds ratio greater than 1 (threshold for trial conclusion of superiority >99%). Results: After excluding 19 participants who withdrew consent, there were 384 patients (mean age, 60 years; 29% female) randomized to the fixed-dose (n = 137), shock-dependent (n = 146), and no (n = 101) hydrocortisone groups; 379 (99%) completed the study and were included in the analysis. The mean age for the 3 groups ranged between 59.5 and 60.4 years; most patients were male (range, 70.6%-71.5%); mean body mass index ranged between 29.7 and 30.9; and patients receiving mechanical ventilation ranged between 50.0% and 63.5%. For the fixed-dose, shock-dependent, and no hydrocortisone groups, respectively, the median organ support-free days were 0 (IQR, -1 to 15), 0 (IQR, -1 to 13), and 0 (-1 to 11) days (composed of 30%, 26%, and 33% mortality rates and 11.5, 9.5, and 6 median organ support-free days among survivors). The median adjusted odds ratio and bayesian probability of superiority were 1.43 (95% credible interval, 0.91-2.27) and 93% for fixed-dose hydrocortisone, respectively, and were 1.22 (95% credible interval, 0.76-1.94) and 80% for shock-dependent hydrocortisone compared with no hydrocortisone. Serious adverse events were reported in 4 (3%), 5 (3%), and 1 (1%) patients in the fixed-dose, shock-dependent, and no hydrocortisone groups, respectively. Conclusions and Relevance: Among patients with severe COVID-19, treatment with a 7-day fixed-dose course of hydrocortisone or shock-dependent dosing of hydrocortisone, compared with no hydrocortisone, resulted in 93% and 80% probabilities of superiority with regard to the odds of improvement in organ support-free days within 21 days. However, the trial was stopped early and no treatment strategy met prespecified criteria for statistical superiority, precluding definitive conclusions. Trial Registration: ClinicalTrials.gov Identifier: NCT02735707