Evaluation of the shiedling in the bunker for the superconducting cavity test at LASA

In the LASA (Laboratorio Acceleratori e Superconduttività Applicata) laboratory of the Milan section of INFN (Istituto Nazionale di Fisica Nucleare) a facility for testing superconducting cavities is operating. The possibility to operate with a generation of radiation up to 10 MeV and more requires a careful evaluation of the shielding efficiency of the existing bunker The calculation was performed with the FLUKA code, the whole cryostat, bunker and ceiling of the building was taken into account. Two hypothesis for the radiation source have been adopted to carry out the calculations: the very conservative hypothesis of 10 MeV electron pencil beam, and the second hypothesis (maybe more realistic) of an isotropic 10 MeV electron source. In the less conservative hypothesis a safe operation is guarantee by the foreseen shielding. The simulations show that even in the most conservative hypothesis a negligible amount of photons can exit the bunker, without interaction with the simulated detectors. In the future, at the starting of the tests in the upgraded configuration, direct measurements will be used to definitely check the shielding adopted

Performance analysis of the European X-ray Free Electron Laser 3.9 GHz superconducting cavities

The limits of performance of the European XFEL 3.9 GHz superconducting cavities were investigated. Most cavities exhibited high field Q slope, reaching the breakdown field at approximately $22\text{ }\text{ }\mathrm{MV}/\mathrm{m}$. We hypothesize that this limit is a feature of high frequency cavities and can be explained by a thermal model incorporating field dependent surface resistance. The results obtained from simulations were in good agreement with experimental data obtained at 2 K

Enceladus and Titan: Emerging Worlds of the Solar System (ESA Voyage 2050 White Paper)

Some of the major discoveries of the recent Cassini-Huygens mission have put Titan and Enceladus firmly on the Solar System map. The mission has revolutionised our view of Solar System satellites, arguably matching their scientific importance with that of their planet. While Cassini-Huygens has made big surprises in revealing Titan's organically rich environment and Enceladus' cryovolcanism, the mission's success naturally leads us to further probe these findings. We advocate the acknowledgement of Titan and Enceladus science as highly relevant to ESA's long-term roadmap, as logical follow-on to Cassini-Huygens. In this white paper, we will outline important science questions regarding these satellites and identify the pertinent science themes we recommend ESA cover during the Voyage 2050 planning cycle. Addressing these science themes would make major advancements to the present knowledge we have about the Solar System, its formation, evolution and likelihood that other habitable environments exist outside the Earth's biosphere

A new biogenerated Rh-based catalyst for aqueous biphasic hydroformylation

A new bio-generated rhodium based system embedded in a peculiar polysaccharide matrix (Rh-EPS), was obtained and purified from cultures of bacterial cells of Klebsiella oxytoca DSM 29614. The product was analyzed with different techniques to obtain information on its structure-property correlation. In order to determine its catalytic activity and selectivity in the aqueous biphasic hydroformylation some olefins were chosen as model substrates, obtaining fine-good results.A new bio-generated rhodium based system embedded in a peculiar polysaccharide matrix (Rh-EPS), was obtained and purified from cultures of bacterial cells of Klebsiella oxytoca DSM 29614. The product was analyzed with different techniques to obtain information on its structure-property correlation. In order to determine its catalytic activity and selectivity in the aqueous biphasic hydroformylation some olefins were chosen as model substrates, obtaining fine-good results

Development of an X-Ray Fluorescence Probe for Inner Cavity Inspection

The ability to detect performance-limiting defects onthe inner surface of superconducting radiofrequency(SRF) niobium cavities, which lead to low quality factorQ0 factor, thermal breakdowns (especially at the equatorwelding seams and the surrounding area), and X-rayradiation (mainly due to sharp geometric defects on theirises) provides a tool of quality control (QC) and failurereason clarification. Detection of failures and defects,especially in early production steps, would significantlyreduce repetition of quite expensive cryogenic RF testsand retreatments of the cavities. Inspection of the innercavity surface by an optical system is an inexpensive anduseful means for surface control and identification ofdangerous or suspicious features [1, 2]. It does notprovide, however, information about material content inthe defect region, which is required for sorting out thecavities with foreign inclusions and for the localisation ofa contamination source in the production cycle.Preliminary diagnostic is usually performed during theQC of niobium sheets resorting to several non-destructivetechniques, e.g. eddy current scanning [3].X-ray fluorescence (XRF) analysis is widely used forelemental and chemical analyses, particularly in theinvestigation of metals. This technique, already employedduring the QC of niobium sheets [4], appears to beentitled for development of a diagnostic tool for thedetection of trace element inclusions on the cavitysurface. Preliminary feasibility tests [5] performed with alow-performance XRF setup, demonstrated that lowamounts (some g) of different metals could be easilydetected when embedded in the niobium matrix. Theseencouraging results have been the first step towards thedevelopment of an XRF tool for the QC of the innersurface of 1.3 GHz SRF cavities. The complicated shape of the cavities and hidden inner surface require, however,development of a special device

Possible remnant interplanetary magnetic field in Titan's ionosphere during Cassini's T39 flyby

International audienceCassini's 39th close flyby of Titan occurred on the 20th December 2007 around 11.33 hours of Saturn local time. Closest approach (CA) took place at 2256:41 UTC at an altitude of 970 km above Titan's surface as Cassini was flying outbound from Saturn. Although the encounter occurred well inside Saturn's magnetosphere, high solar wind pressure conditions a few hours before CA made the Kronian magnetopause to recede inside the orbit of the moon, exposing it to the shocked interplanetary magnetic field (IMF) for more than an hour. Although the external layers of draped magnetic field within Titan's induced magnetosphere have polarities compatible with Kronian fields, the magnetic field within the moon's collisional ionosphere coincides with the expected draped IMF fossil lines. In this work we discuss the origin and lifetime of these ionospheric fields and compare these results with those obtained during the T32 flyby, when fossil fields were first reported

Сибирский Вестник № 253

The aim of this project is to develop a system for defectdetection by means of X-ray fluorescence (XRF) analysis.XRF is a high sensitivity spectroscopy technique allowingthe detection of trace element content, such as the fewmicrogram impurities, responsible for low cavityperformances if embedded in the equatorial region duringcavity manufacturing. The proposed setup is customizedon 1.3 GHz TESLA-type niobium cavities: both thedetector and the X-ray excitation source are miniaturizedso to allow the probe to enter within the 70 mm irisdiameter and aside of the HOM couplers. The detectionexcitationgeometry is focused on cavity cell equatorsurface located at about 103 mm from the cavity axis,with an intrinsic spot-size of about 10 mm. Themeasuring head will be settled on a high angularresolution optical inspection system at DESY, exploitingthe experience of OBACHT. Defect position is obtainedby means of angular inner surface scanning. Quantitativedetermination of defect content can be carried out bymeans of the so called fundamental parameters techniquewith a Niobium standard calibration

R&D on High QE Photocathodes at INFN LASA

We present the recent activities on antimonide and telluride alkali based photocathodes at INFN LASA. The R on Cs₂Te materials is focused on investigating effects of material thickness and growth procedures on the photocathodes performances during operation in RF guns. We aim to improve thermal emittance and long term stability of these films. The more recent work on alkali antimonide showed the need for substantial improvements in stability and QE during operation. We present here our recent achievements and plans for future activities

Dynamics of Saturn's magnetodisk near Titan's orbit: Comparison of Cassini magnetometer observations from real and virtual Titan flybys

We analyze the variability of the ambient magnetospheric field along Titan’s orbit at 20.3 Saturn radii. However, while our preceding study (Simon et al., 2010) focused on Cassini magnetometer observations from the 62 Titan flybys (TA–T62) between October 2004 and October 2009, the present work discusses magnetic field data that were collected near Titan’s orbit when the moon was far away. In analogy to the observations during TA–T62, the magnetospheric fields detected during these 79 ‘‘virtual’’ Titan flybys are strongly affected by the presence of Saturn’s bowl-shaped and highly dynamic magnetodisk current sheet. We therefore provide a systematic classification of the magnetic field observations as magnetodisk current sheet or lobe-type scenarios. Among the 141 (62 real+79 virtual) crossings of Titan’s orbit between July 2004 and December 2009, only 17 encounters (9 real+8 virtual) took place within quiet, magnetodisk lobe-type fields. During another 50 encounters (21 real+29 virtual), rapid transitions between current sheet and lobe fields were observed around the moon’s orbital plane. Most of the encounters (54¼22 real+32 virtual) occurred when Titan’s orbit was embedded in highly distorted current sheet fields, thereby invalidating the frequently applied idealized picture of Titan interacting with a homogeneous and stationary magnetospheric background field. The locations of real and virtual Titan flybys are correlated to each other. Each of the 62 real Titan flybys possesses at least one virtual counterpart that occurred shortly before or after the real encounter and at nearly the same orbital position. A systematic comparison between Cassini magnetometer observations from the real Titan flybys and their virtual companions suggests that there is no clear evidence of Titan exerting a significant level of control on the vertical oscillatory motion of the magnetodisk near its orbit.Fil: Simon, Sven. University of Cologne; AlemaniaFil: Wennmacher, Alexandre. University of Cologne; AlemaniaFil: Neubauer, Fritz M.. University of Cologne; AlemaniaFil: Bertucci, Cesar. Consejo Nacional de Investigaciónes Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Astronomía y Física del Espacio. - Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Astronomía y Física del Espacio; ArgentinaFil: Kriegel, Hendrik. Institute for Theoretical Physics; AlemaniaFil: Russell, Christopher T.. University of California; Estados UnidosFil: Dougherty, Michele K.. Imperial College London; Reino Unid