Rotational velocities of A-type stars II. Measurement of vsini in the northern hemisphere

This work is the second part of the set of measurements of vsini for A-type stars, begun by Royer et al. (2002). Spectra of 249 B8 to F2-type stars brighter than V=7 have been collected at Observatoire de Haute-Provence (OHP). Fourier transforms of several line profiles in the range 4200--4600 A are used to derive vsini from the frequency of the first zero. Statistical analysis of the sample indicates that measurement error mainly depends on vsini and this relative error of the rotational velocity is found to be about 5% on average. The systematic shift with respect to standard values from Slettebak et al. (1975), previously found in the first paper, is here confirmed. Comparisons with data from the literature agree with our findings: vsini values from Slettebak et al. are underestimated and the relation between both scales follows a linear law: vsini(new) = 1.03 vsini(old) + 7.7. Finally, these data are combined with those from the previous paper (Royer et al. 2002), together with the catalogue of Abt & Morrell (1995). The resulting sample includes some 2150 stars with homogenized rotational velocities.Comment: 16 pages, includes 13 figures, accepted in A&

Statistical simulations of machine errors for LINAC4

LINAC 4 is a normal conducting H- linac proposed at CERN to provide a higher proton flux to the CERN accelerator chain. It should replace the existing LINAC 2 as injector to the Proton Synchrotron Booster and can also operate in the future as the front end of the SPL, a 3.5 GeV Superconductingg Proton Linac. LINAC 4 consists of a Radio-Frequency Quadrupole, a chopper line, a Drift Tube Linac (DTL) and a Cell Coupled DTL all operating at 352 MHz and finally a Side Coupled Linac at 704 MHz. Beam dynamics was studied and optimized performing end-to-end simulations. This paper presents statistical simulations of machine errors which were performed in order to validate the proposed design

Measurement of fast and thermal neutron flux from the d + D reaction using the activation method

LPSC-acc ;

A photon calorimeter using lead tungstate crystals for the CEBAF Hall A Compton polarimeter

The performances of the calorimeter of the Jlab Hall A Compton Polarimeter have been measured using the Mainz tagged photon beam.Comment: 13 page

End-to-End Beam Dynamics for CERN LINAC4

LINAC 4 is a normal conducting H- linac which aims to intensify the proton flux available for the CERN accelerator complex. This injector is designed to accelerate a 65 mA beam of H- ions up to 160 MeV for injection into the CERN Proton Synchrotron Booster. The acceleration is done in three stages : up to 3 MeV with a Radio Frequency Quadrupole (the IPHI RFQ) operating at 352 MHz, then continued to 90 MeV with drift-tube structures at 352 MHz (conventional Alvarez and Cell Coupled Drift Tube Linac) and, finally with a Side Coupled Linac at 704 MHz. The accelerator is completed by a chopper line at 3 MeV and a transport and matching line to the PS booster. After the overall layout was determined based on general consideration of beam dynamics and RF, a global optimisation based on end-to-end simulation has refined some design choices. The results and lessons learned from the end-to-end simulations are reported in this paper

First electron beam polarization measurements with a Compton polarimeter at Jefferson Laboratory

A Compton polarimeter has been installed in Hall A at Jefferson Laboratory. This letter reports on the first electron beam polarization measurements performed during the HAPPEX experiment at an electron energy of 3.3 GeV and an average current of 40 $\mu$A. The heart of this device is a Fabry-Perot cavity which increased the luminosity for Compton scattering in the interaction region so much that a 1.4% statistical accuracy could be obtained within one hour, with a 3.3% total error

Error study of CERN Linac 4

LINAC 4 is a normal conducting H- structure proposed to intensify the proton flux currently available for the CERN accelerator chain. This linac is designed to accelerate a 65 mA beam up to 160 MeV to be injected into the CERN Proton Synchrotron Booster. The acceleration is performed up to 3 MeV by a Radio-Frequency Quadrupole resonating at 352 MHz followed by a serie of two drift tube systems (conventional Alvarez and Cell Coupled Drift Tube Linac) boosting the beam up to 90 MeV at 352 MHz and finished by a Side Coupled Linac at 704 MHz. Beam dynamics was studied and optimized performing end-to-end simulations. Robustness of this design was verified by modelling machine errors. This paper presents the results of this error study.Comment: Poster presented to European Particle Accelerator Conference (EPAC'06), Edinburgh, Scotland, 26-30 June 200

Status of the Super-B factory Design

The SuperB international team continues to optimize the design of an electron-positron collider, which will allow the enhanced study of the origins of flavor physics. The project combines the best features of a linear collider (high single-collision luminosity) and a storage-ring collider (high repetition rate), bringing together all accelerator physics aspects to make a very high luminosity of 10$^{36}$ cm$^{-2}$ sec$^{-1}$. This asymmetric-energy collider with a polarized electron beam will produce hundreds of millions of B-mesons at the $\Upsilon$(4S) resonance. The present design is based on extremely low emittance beams colliding at a large Piwinski angle to allow very low $\beta_y^\star$ without the need for ultra short bunches. Use of crab-waist sextupoles will enhance the luminosity, suppressing dangerous resonances and allowing for a higher beam-beam parameter. The project has flexible beam parameters, improved dynamic aperture, and spin-rotators in the Low Energy Ring for longitudinal polarization of the electron beam at the Interaction Point. Optimized for best colliding-beam performance, the facility may also provide high-brightness photon beams for synchrotron radiation applications

Spectroscopic survey of the Galaxy with Gaia I. Design and performance of the Radial Velocity Spectrometer

The definition and optimisation studies for the Gaia satellite spectrograph, the Radial Velocity Spectrometer (RVS), converged in late 2002 with the adoption of the instrument baseline. This paper reviews the characteristics of the selected configuration and presents its expected performance. The RVS is a 2.0 by 1.6 degree integral field spectrograph, dispersing the light of all sources entering its field of view with a resolving power R=11 500 over the wavelength range [848, 874] nm. The RVS will continuously and repeatedly scan the sky during the 5 years of the Gaia mission. On average, each source will be observed 102 times over this period. The RVS will collect the spectra of about 100-150 million stars up to magnitude V~17-18. At the end of the mission, the RVS will provide radial velocities with precisions of ~2 km/s at V=15 and \~15-20 km/s at V=17, for a solar metallicity G5 dwarf. The RVS will also provide rotational velocities, with precisions (at the end of the mission) for late type stars of sigma_vsini ~5 km/s at V~15 as well as atmospheric parameters up to V~14-15. The individual abundances of elements such as Silicon and Magnesium, vital for the understanding of Galactic evolution, will be obtained up to V~12-13. Finally, the presence of the 862.0 nm Diffuse Interstellar Band (DIB) in the RVS wavelength range will make it possible to derive the three dimensional structure of the interstellar reddening.Comment: 17 pages, 9 figures, accepted for publication in MNRAS. Fig. 1,2,4,5, 6 in degraded resolution; available in full resolution at http://blackwell-synergy.com/links/doi/10.1111/j.1365-2966.2004.08282.x/pd