Distributed Radiation Monitoring System for Linear Accelerators based on CAN Bus

Abstract—Gamma and neutron radiation is produced during the normal operation of linear accelerators like Free-Electron Laser in Hamburg (FLASH) or X-ray Free Electron Laser (X-FEL). Gamma radiation cause general degeneration of electronics devices and neutron fluence can be a reason of soft error in memories and microcontrollers. X-FEL accelerator will be built only in one tunnel, therefore most of electronic control systems will be placed in radiation environment. Exposing control systems to radiation may lead to many errors and unexpected failure of the whole accelerator system. Thus, the radiation monitoring system able to monitor radiation doses produced near controlling systems is crucial. Knowledge of produced radiation doses allows to detect errors caused by radiation, make plans of essential exchange of control systems and prevent accelerator from serious damages. The paper presents the project of radiation monitoring system able to monitor radiation environment in real time

Spin dynamics in a Curie-switch

Ferromagnetic resonance properties of F$_1$/f/F$_2$/AF multilayers, where weakly ferromagnetic spacer f is sandwiched between strongly ferromagnetic layers F$_1$ and F$_2$, with F$_1$ being magnetically soft and F$_2$ - magnetically hard due to exchange pinning to antiferromagnetic layer AF, are investigated. Spacer-mediated exchange coupling is shown to strongly affect the resonance fields of both F$_1$ and F$_2$ layers. Our theoretical calculations as well as measurements show that the key magnetic parameters of the spacer, which govern the ferromagnetic resonance in F$_1$/f/F$_2$/AF, are the magnetic exchange length ($\Lambda$), effective saturation magnetization at $T=0$ $(m_0)$, and effective Curie temperature ($T_{\text{C}}^{\text{eff}}$). The values of these key parameters are deduced from the experimental data for multilayers with f = Ni$_x$Cu$_{100-x}$, for the key ranges in Ni-concentration ($x=54\div70$ at. %) and spacer thickness ($d=3\div 6$ nm). The results obtained provide a deeper insight into thermally-controlled spin precession and switching in magnetic nanostructures, with potential applications in spin-based oscillators and memory devices.Comment: 9 pages, 7 figures, 24 reference

Klasifikacija tehničkih materijala prema klasama obradivosti kod hidroabrazivnog rezanja

This paper presents the major cutting knowledge, the opinion data and the results of actual theoretic parameters solutions and the current results, estimated by contemporary needs of hydro abrasive cutting technology. Here is a newly opened and discussed question of current data terminology disunity in the area of metrology topography surfaces of cutting walls created by abrasive waterjet.U radu su prezentirana temeljna znanja, razmišljanja i rezultati teorijskih rješenja vezano uz trenutne procijenjene suvremene potrebe za hidroabrazivnom tehnologijom rezanja. Ovdje je i ponovo otvoreno pitanje trenutne terminologije u području mjeriteljstva topografi je površina dobivenih rezanjem abrazivnim vodenim mlazom

Purification and characterization of pre-mRNA splicing factor SF2 from HeLa cells

SF2, an activity necessary for 5' splice site cleavage and lariat formation during pre-mRNA splicing in vitro, has been purified to near homogeneity from HeLa cells. The purest fraction contains only two related polypeptides of 33 kD. This fraction is sufficient to complement an S100 fraction, which contains the remaining splicing factors, to splice several pre-mRNAs. The optimal amount of SF2 required for efficient splicing depends on the pre-mRNA substrate. SF2 is distinct from the hnRNP A1 and U1 snRNP a polypeptides, which are similar in size. Endogenous hnRNA copurifies with SF2, but this activity does not appear to have an essential RNA component. SF2 appear to be necessary for the assembly or stabilization of the earliest specific prespliceosome complex, although in the absence of other components, it can bind RNA in a nonspecific manner. SF2 copurifies with an activity that promotes the annealing of complementary RNAs. Thus, SF2 may promote specific RNA-RNA interactions between snRNAs and pre-mRNA, between complementary snRNA regions, and/or involving intramolecular pre-mRNA helices. Other purified proteins with RNA annealing activity cannot substitute for SF2 in the splicing reaction

Use of tunable nanopore blockade rates to investigate colloidal dispersions

Tunable nanopores in elastomeric membranes have been used to study the dependence of ionic current blockade rate on the concentration and electrophoretic mobility of particles in aqueous suspensions. A range of nanoparticle sizes, materials and surface functionalities has been tested. Using pressure-driven flow through a pore, the blockade rate for 100 nm carboxylated polystyrene particles was found to be linearly proportional to both transmembrane pressure (controlled between 0 and 1.8 kPa) and particle concentration (between 7 x 10^8 and 4.5 x 10^10 mL^-1). This result can be accurately modelled using Nernst-Planck transport theory. Using only an applied potential across a pore, the blockade rates for carboxylic acid and amine coated 500 nm and 200 nm silica particles were found to correspond to changes in their mobility as a function of the solution pH. Scanning electron microscopy and confocal microscopy have been used to visualise changes in the tunable nanopore geometry in three dimensions as a function of applied mechanical strain. The pores observed were conical in shape, and changes in pore size were consistent with ionic current measurements. A zone of inelastic deformation adjacent to the pore has been identified as critical in the tuning process

Compact single-shot electro-optic detection system for THz pulses with femtosecond time resolution at MHz repetition rates

Electro-optical detection has proven to be a valuable technique to study temporal profiles of THz pulses with pulse durations down to femtoseconds. As the Coulomb field around a relativistic electron bunch resembles the current profile, electro-optical detection can be exploited for non-invasive bunch length measurements at accelerators. We have developed a very compact and robust electro-optical detection system based on spectral decoding for bunch length monitoring at the European XFEL with single-shot resolution better than 200~fs. Apart from the GaP crystal and the corresponding laser optics at the electron beamline, all components are housed in 19\" chassis for rack mount and remote operation inside the accelerator tunnel. An advanced laser synchronization scheme based on radio-frequency down-conversion has been developed for locking a custom-made Yb-fiber laser to the radio-frequency of the European XFEL accelerator. In order to cope with the high bunch repetition rate of the superconducting accelerator, a novel linear array detector (KALYPSO) has been employed for spectral measurements of the Yb-fiber laser pulses at frame rates of up to 2.26~MHz. In this paper, we describe all sub-systems of the electro-optical detection system as well as the measurement procedure in detail, and discuss first measurement results of longitudinal bunch profiles of around 400~fs (rms) with an arrival-time jitter of 35~fs (rms)

Analiza topografije površina titanove legure nakon rezanja vodenim mlazom pomoću spektralne analize

Experimental study of a titan grade 2 surface topography prepared by abrasive waterjet cutting is performed using methods of the spectral analysis. Topographic data are acquired by means of the optical profilometr MicroProf®FRT. Estimation of the areal power spectral density of the studied surface is carried out using the periodogram method combined with the Welch´s method. Attention is paid to a structure of the areal power spectral density, which is characterized by means of the angular power spectral density. This structure of the areal spectral density is linked to the fi ne texture of the surface studied.Eksperimentalna studija površine titana klase 2 dobivene abrazivnim rezanjem vodenim mlazom je provedena korištenjem metode spektralne analize. Topografski su podaci prikupljeni pomoću optičkog profi lometra MicroProf®FRT. Procjena površinske snage spektralne gustoće je provedena periodogram metodom u kombinaciji sa Welch metodom. Pozornost je posvećena površinskoj snazi spektralne gustoće koja je karakterizirana pomoću kutnih spektara gustoće snage. Struktura površinskog spektra gustoće je povezana sa istraživanom fi nom teksturom površine

Proceso de diseño del Centro de Interpretación Cañadón del Duraznillo, Golfo San Jorge, Santa Cruz, Argentina

Este trabajo examina el proceso de diseño del Centro de Interpretación Cañadón del Duraznillo, ubicado en el Golfo San Jorge, Santa Cruz, Argentina. Desde los primeros esbozos morfológicos hasta la selección de materiales y detalles constructivos, dicho proceso fue guiado por simulaciones y estudios de las condiciones ambientales específicas a este caso particular, como así también recomendaciones generales apropiadas para este clima y localización geográfica a partir de bibliografía especializada y experiencias proyectuales anteriores. Los estudios desarrollados incluyeron simulaciones de asoleamiento, radiación solar, viento, iluminación natural y características térmicas de los materiales de la envolvente. El objetivo de este artículo es presentar un caso específico de arquitectura de bajo impacto ambiental y alto grado de eficiencia energética y examinar la productividad metodológica del diseño arquitectónico asistido por estudios en un laboratorio de estudios bioambientales.Fil: Kozak, Daniel Matias. Consejo Nacional de Investigaciones Cientificas y Tecnicas. Oficina de Coordinacion Administrativa Saavedra 15. Centro de Estudios Urbanos y Regionales; ArgentinaFil: de Schiller, S.. Universidad de Buenos Aires. Facultad de Arquitectura y Urbanismo. Centro de Investigacion Habitat y Energia; ArgentinaFil: Evans, J. M.. Universidad de Buenos Aires. Facultad de Arquitectura y Urbanismo. Centro de Investigacion Habitat y Energia; ArgentinaFil: Adamo, G.. Universidad de Buenos Aires. Facultad de Arquitectura y Urbanismo. Centro de Investigacion Habitat y Energia; ArgentinaFil: Abálsamo, D.. Universidad de Buenos Aires. Facultad de Arquitectura y Urbanismo. Centro de Investigacion Habitat y Energia; Argentin

Dimer coverings on the Sierpinski gasket with possible vacancies on the outmost vertices

We present the number of dimers $N_d(n)$ on the Sierpinski gasket $SG_d(n)$ at stage $n$ with dimension $d$ equal to two, three, four or five, where one of the outmost vertices is not covered when the number of vertices $v(n)$ is an odd number. The entropy of absorption of diatomic molecules per site, defined as $S_{SG_d}=\lim_{n \to \infty} \ln N_d(n)/v(n)$, is calculated to be $\ln(2)/3$ exactly for $SG_2(n)$. The numbers of dimers on the generalized Sierpinski gasket $SG_{d,b}(n)$ with $d=2$ and $b=3,4,5$ are also obtained exactly. Their entropies are equal to $\ln(6)/7$, $\ln(28)/12$, $\ln(200)/18$, respectively. The upper and lower bounds for the entropy are derived in terms of the results at a certain stage for $SG_d(n)$ with $d=3,4,5$. As the difference between these bounds converges quickly to zero as the calculated stage increases, the numerical value of $S_{SG_d}$ with $d=3,4,5$ can be evaluated with more than a hundred significant figures accurate.Comment: 35 pages, 20 figures and 1 tabl