Ferrite-damped higher-order mode study in the Brookhaven energy-recovery linac cavity

A superconducting energy-recovery linac (ERL) is under construction at Brookhaven National Laboratory (BNL) to serve as a test bed for an application to upgrades of the Relativistic Heavy Ion Collider (RHIC). The damping of higher-order modes in the superconducting five-cell cavity is of paramount importance and represents the topic of this paper. Achieving the damping by the exclusive use of two ferrite absorbers and the adoption of a space-saving step instead of the conventional taper are part of the exploratory study. Absorber properties which are portable to simulation programs for the ERL cavity have been obtained by measuring the absorber as a ferrite-loaded pill-box cavity. Measured and simulated results for the lowest dipole modes in the prototype copper cavity with one absorber are discussed. First room-temperature measurements of the fully assembled niobium cavity string are presented which confirm the effective damping of higher-order modes by the ferrite absorbers, and which give credibility to the simulated R over Q's in the ERL.open1

Orbital evidence for more widespread carbonate-bearing rocks on Mars

Carbonates are key minerals for understanding ancient Martian environments because they are indicators of potentially habitable, neutral-to-alkaline water and may be an important reservoir for paleoatmospheric CO_2. Previous remote sensing studies have identified mostly Mg-rich carbonates, both in Martian dust and in a Late Noachian rock unit circumferential to the Isidis basin. Here we report evidence for older Fe- and/or Ca-rich carbonates exposed from the subsurface by impact craters and troughs. These carbonates are found in and around the Huygens basin northwest of Hellas, in western Noachis Terra between the Argyre basin and Valles Marineris, and in other isolated locations spread widely across the planet. In all cases they cooccur with or near phyllosilicates, and in Huygens basin specifically they occupy layered rocks exhumed from up to ~5 km depth. We discuss factors that might explain their observed regional distribution, arguments for why carbonates may be even more widespread in Noachian materials than presently appreciated and what could be gained by targeting these carbonates for further study with future orbital or landed missions to Mars

Charge dependent azimuthal correlations in Pb--Pb collisions at sNN=2.76\sqrt{s_{NN}} = 2.76 TeV

Separation of charges along the extreme magnetic field created in non-central relativistic heavy--ion collisions is predicted to be a signature of local parity violation in strong interactions. We report on results for charge dependent two particle azimuthal correlations with respect to the reaction plane for Pb--Pb collisions at $\sqrt{s_{NN}} = 2.76$ TeV recorded in 2010 with ALICE at the LHC. The results are compared with measurements at RHIC energies and against currently available model predictions for LHC. Systematic studies of possible background effects including comparison with conventional (parity-even) correlations simulated with Monte Carlo event generators of heavy--ion collisions are also presented.Comment: Published in the proceedings of "Quark Matter 2011", Annecy-Franc

Overcoming the Challenges Associated with Image-based Mapping of Small Bodies in Preparation for the OSIRIS-REx Mission to (101955) Bennu

The OSIRIS-REx Asteroid Sample Return Mission is the third mission in NASA's New Frontiers Program and is the first U.S. mission to return samples from an asteroid to Earth. The most important decision ahead of the OSIRIS-REx team is the selection of a prime sample-site on the surface of asteroid (101955) Bennu. Mission success hinges on identifying a site that is safe and has regolith that can readily be ingested by the spacecraft's sampling mechanism. To inform this mission-critical decision, the surface of Bennu is mapped using the OSIRIS-REx Camera Suite and the images are used to develop several foundational data products. Acquiring the necessary inputs to these data products requires observational strategies that are defined specifically to overcome the challenges associated with mapping a small irregular body. We present these strategies in the context of assessing candidate sample-sites at Bennu according to a framework of decisions regarding the relative safety, sampleability, and scientific value across the asteroid's surface. To create data products that aid these assessments, we describe the best practices developed by the OSIRIS-REx team for image-based mapping of irregular small bodies. We emphasize the importance of using 3D shape models and the ability to work in body-fixed rectangular coordinates when dealing with planetary surfaces that cannot be uniquely addressed by body-fixed latitude and longitude.Comment: 31 pages, 10 figures, 2 table

Measurement of pion, kaon and proton production in proton-proton collisions at s=7\sqrt{s}=7 TeV

The measurement of primary $\pi^{\pm}$, K$^{\pm}$, p and $\overline{p}$ production at mid-rapidity ($|y| <$ 0.5) in proton-proton collisions at $\sqrt{s} = 7$ TeV performed with ALICE (A Large Ion Collider Experiment) at the Large Hadron Collider (LHC) is reported. Particle identification is performed using the specific ionization energy loss and time-of-flight information, the ring-imaging Cherenkov technique and the kink-topology identification of weak decays of charged kaons. Transverse momentum spectra are measured from 0.1 up to 3 GeV/$c$ for pions, from 0.2 up to 6 GeV/$c$ for kaons and from 0.3 up to 6 GeV/$c$ for protons. The measured spectra and particle ratios are compared with QCD-inspired models, tuned to reproduce also the earlier measurements performed at the LHC. Furthermore, the integrated particle yields and ratios as well as the average transverse momenta are compared with results at lower collision energies.Comment: 33 pages, 19 captioned figures, 3 tables, authors from page 28, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/156

Efficient NiII2LnIII2 electrocyclization catalysts for the synthesis of trans-4,5-diaminocyclopent-2-enones from 2-furaldehyde and primary or secondary amines

A series of heterometallic coordination clusters (CCs) [NiII2LnIII2(L1)4Cl2(CH3CN)2] 2CH3CN [Ln = Y (1Y), Sm (1Sm), Eu (1Eu), Gd (1Gd), or Tb (1Tb)] were synthesized by the reaction of (E)-2-(2-hydroxy-3-methoxybenzylidene-amino)phenol) (H2L1) with NiCl2·6(H2O) and LnCl3·x(H2O) in the presence of Et3N at room temperature. These air-stable CCs can be obtained in very high yields from commercially available materials and are efficient catalysts for the room-temperature domino ring-opening electrocyclization synthesis of trans-4,5-diaminocyclopent-2-enones from 2-furaldehyde and primary or secondary amines under a non-inert atmosphere. Structural modification of the catalyst to achieve immobilization or photosensitivity is possible without deterioration in catalytic activity

An ep collider with E/sub cm/=1 TeV in a VLHC booster tunnel

The low field option for the VLHC includes a 3 TeV proton booster with a circumference of 34 km. The authors are studying the option of an electron ring to fit in this tunnel which can produce ep collisions with a luminosity of 1 fb{sup {minus}1}/yr with a center of mass energy of 1 TeV. The machine would utilize superconducting rf and small low field magnets for the {approximately} 80 GeV electron beam. They describe the vacuum chamber/magnet system, rf power supply requirements, vacuum chamber cooling, interaction regions and installation of the facility in the tunnel, as well as provide preliminary estimates of beam stability and lifetimes

UNIFYING PRACTICAL UNCERTAINTY REPRESENTATIONS: I. GENERALIZED P-BOXES

Pre-print of final version.International audienceThere exist several simple representations of uncertainty that are easier to handle than more general ones. Among them are random sets, possibility distributions, probability intervals, and more recently Ferson's p-boxes and Neumaier's clouds. Both for theoretical and practical considerations, it is very useful to know whether one representation is equivalent to or can be approximated by other ones. In this paper, we define a generalized form of usual p-boxes. These generalized p-boxes have interesting connections with other previously known representations. In particular, we show that they are equivalent to pairs of possibility distributions, and that they are special kinds of random sets. They are also the missing link between p-boxes and clouds, which are the topic of the second part of this study