A primary electron beam facility at CERN

This paper describes the concept of a primary electron beam facility at CERN, to be used for dark gauge force and light dark matter searches. The electron beam is produced in three stages: A Linac accelerates electrons from a photo-cathode up to 3.5 GeV. This beam is injected into the Super Proton Synchrotron, SPS, and accelerated up to a maximum energy of 16 GeV. Finally, the accelerated beam is slowly extracted to an experiment, possibly followed by a fast dump of the remaining electrons to another beamline. The beam parameters are optimized using the requirements of the Light Dark Matter eXperiment (LDMX) as benchmark.Comment: 3 pages, 3 figure

On the relation between circular velocity and central velocity dispersion in high and low surface brightness galaxies

In order to investigate the correlation between the circular velocity Vc and the central velocity dispersion of the spheroidal component sigma_c, we analyzed these quantities for a sample of 40 high surface brightness disc galaxies (hereafter HSB), 8 giant low surface brightness spiral galaxies (hereafter LSB), and 24 elliptical galaxies characterized by flat rotation curves. We find that the Vc-sigma_c relation is descri ed by a linear law out to velocity dispersions as low as sigma_c~50km/s, while in previous works a power law was adopted for galaxies with sigma_c>80k/ms. Elliptical galaxies with Vc based on dynamical models or directly derived from the HI rotation curves follow the same relation as the HSB galaxies in the Vc-sigma_c plane. On the contrary, the LSB galaxies follow a different relation, since most of them show either higher Vc (or lower sigma_c) with respect to the HSB galaxies. This argues against the relevance of baryon collapse in the radial density profile of the dark matter haloes of LSB galaxies. (abridged)Comment: 18 pages, 4 figures, ApJ in pres

The role of quenching time in the evolution of the mass-size relation of passive galaxies from the WISP survey

We analyze how passive galaxies at z $\sim$ 1.5 populate the mass-size plane as a function of their stellar age, to understand if the observed size growth with time can be explained with the appearance of larger quenched galaxies at lower redshift. We use a sample of 32 passive galaxies extracted from the Wide Field Camera 3 Infrared Spectroscopic Parallel (WISP) survey with spectroscopic redshift 1.3 $\lesssim$ z $\lesssim$ 2.05, specific star-formation rates lower than 0.01 Gyr$^{-1}$, and stellar masses above 4.5 $\times$ 10$^{10}$ M$_\odot$. All galaxies have spectrally determined stellar ages from fitting of their rest-frame optical spectra and photometry with stellar population models. When dividing our sample into young (age $\leq$ 2.1 Gyr) and old (age $>$ 2.1 Gyr) galaxies we do not find a significant trend in the distributions of the difference between the observed radius and the one predicted by the mass-size relation. This result indicates that the relation between the galaxy age and its distance from the mass-size relation, if it exists, is rather shallow, with a slope alpha $\gtrsim$ -0.6. At face value, this finding suggests that multiple dry and/or wet minor mergers, rather than the appearance of newly quenched galaxies, are mainly responsible for the observed time evolution of the mass-size relation in passive galaxies.Comment: Accepted for publication in ApJ Letters; 6 pages, 3 figures, 1 tabl

Kinematic Evidence of Minor Mergers in Normal Sa Galaxies: NGC3626, NGC3900, NGC4772 and NGC5854

BVRI and H-alpha imaging and long-slit optical spectroscopic data are presented for four morphologically normal and relatively isolated Sa galaxies, NGC3626, NGC3900, NGC4772 and NGC5854. VLA HI synthesis imaging is presented for the first 3 objects. In all 4 galaxies, evidence of kinematic decoupling of ionized gas components is found; the degree and circumstances of the distinct kinematics vary from complete counterrotation of all of the gas from all of the stars (NGC3626) to nuclear gas disks decoupled from the stars (NGC5854) to anomalous velocity central gas components (NGC3900 and NGC4772). In the 3 objects mapped in HI, the neutral gas extends far beyond the optical radius, R_HI/R_25 > 2. In general, the HI surface density is very low and the outer HI is patchy and asymmetric or found in a distinct ring, exterior to the optical edge. While the overall HI velocity fields are dominated by circular motions, strong warps are suggested in the outer regions. Optical imaging is also presented for NGC 4138 previously reported by Jore et al. (1996) to show counterrotating stellar components. The multiwavelength evidence is interpreted in terms of the kinematic "memory" of past minor mergers in objects that otherwise exhibit no morphological signs of interaction.Comment: 26 pages, 15 figures, accepted for publication in Astron. J., postscript figures available at ftp://culebra.tn.cornell.edu/pub/haynes/figures.tar.g

The Tully-Fisher Relation of Barred Galaxies

We present new data exploring the scaling relations, such as the Tully-Fisher relation (TFR), of bright barred and unbarred galaxies. A primary motivation for this study is to establish whether barredness correlates with, and is a consequence of, virial properties of galaxies. Various lines of evidence suggest that dark matter is dominant in disks of bright unbarred galaxies at 2.2 disk scale lengths, the point of peak rotation for a pure exponential disk. We test the hypothesis that the TF plane of barred high surface brightness galaxies is offset from the mean TFR of unbarred galaxies, as might be expected if barred galaxies are ``maximal'' in their inner parts. We use existing and new TF data to search for basic structural differences between barred and unbarred galaxies. Our new data consist of 2-dimensional Halpha velocity fields derived from SparsePak integral field spectroscopy (IFS) and V,I-band CCD images collected at the WIYN Observatory for 14 strongly barred galaxies. We use WIYN/SparsePak (2-D) velocity fields to show that long-slit (1-D) spectra yield reliable circular speed measurements at or beyond 2.2 disk scale lengths, far from any influence of the bar. This enables us to consider line width measurements from extensive TF surveys which include barred and nonbarred disks and derive detailed scaling relation comparisons. We find that for a given luminosity, barred and unbarred galaxies have comparable structural and dynamical parameters, such as peak velocities, scale lengths, or colors. In particular, the location of a galaxy in the TF plane is independent of barredness. In a global dynamical sense, barred and unbarred galaxies behave similarly and are likely to have, on average, comparable fractions of luminous and dark matter at a given radius. (abridged)Comment: Accepted for publication in the ApJ (September 1, 2003 issue, v594). Appendix figures with I-band image and superimposed 2-D velocity field plus rotation curves must be downloaded separately (due to size constraints) from http://www.astro.ubc.ca/people/courteau/public/courteau03_TFbars.ps.g

Status of the CTF3 commissioning

The Preliminary Phase of the new CLIC Test Facility CTF3 consists of a low-charge demonstration of the electron bunch train combination process on which the CLIC drive beam generation scheme is based. The principle of the combination relies on the injection of short electron bunches into an isochronous ring using RF deflecting cavities. The commissioning of this facility started in September 2001, with alternating periods of installation work and beam studies. In this paper, we present the status of the facility, the first beam measurements and the next steps towards the completion of the experiment

Bunch Compressor Performances at the CLIC Test Facility

The Test Facility of the "Compact Linear Collider" (CLIC) at CERN (CTF), has to prove the feasibility of transporting high charge beams through decelerating structures at 30 GHz to create RF power. This RF power is used to supply, in the final scheme, the cavities of the main linac. To optimise this power generation, a bunch compressor has been installed in the test line. This compressor shortens the electron bunches after creation and acceleration in the RF gun. The compressed bunches are then accelerated by a high gradient cavity (50 MV/m) and transported to a 30 GHz cavity. Compressed bunch length mesurements showed that lengths of 0.6 mm (rms) were obtained at the entrance of 30 GHz cavity for a 10 nC beam. Compression of electron bunches of charges between 2 and 17 nC have also been measured. Emittance measurements were done to study the transverse effects of the bunch compressor on the beam. The use of the code PARMELA allowed the design and optimisation of the chicane. The simulations results have been compared to the experimental measurements

The first confirmed record of the Atlantic blue crab Callinectes sapidus Rathbun, 1896 (Decapoda, Brachyura) from Maltese waters

The invasive portunid species Callinectes sapidus is hereby recorded for the first time from Maltese waters, thus updating the known distribution of this decapod of Atlantic origin within the Mediterranean. Potential introduction pathways of the species to Maltese waters are discussed

Implementing Groundness Analysis with Definite Boolean Functions

The domain of definite Boolean functions, Def, can be used to express the groundness of, and trace grounding dependencies between, program variables in (constraint) logic programs. In this paper, previously unexploited computational properties of Def are utilised to develop an efficient and succinct groundness analyser that can be coded in Prolog. In particular, entailment checking is used to prevent unnecessary least upper bound calculations. It is also demonstrated that join can be defined in terms of other operations, thereby eliminating code and removing the need for preprocessing formulae to a normal form. This saves space and time. Furthermore, the join can be adapted to straightforwardly implement the downward closure operator that arises in set sharing analyses. Experimental results indicate that the new Def implementation gives favourable results in comparison with BDD-based groundness analyses

Feasibility and effectiveness assessment of sars-cov-2 antigenic tests in mass screening of a pediatric population and correlation with the kinetics of viral loads

The gold standard for diagnosis of SARS-CoV-2 infection has been nucleic acid amplification tests (NAAT). However, rapid antigen detection kits (Ag-RDTs), may offer advantages over NAAT in mass screening, generating results in minutes, both as laboratory-based test or point-of-care (POC) use for clinicians, at a lower cost. We assessed two different POC Ag-RDTs in mass screening versus NAAT for SARS-CoV-2 in a cohort of pediatric patients admitted to the Pediatric Emergency Unit of IRCCS—Polyclinic of Sant’Orsola, Bologna (from November 2020 to April 2021). All patients were screened with nasopharyngeal swabs for the detection of SARS-CoV-2-RNA and for antigen tests. Results were obtained from 1146 patients. The COVID-19 Ag FIA kit showed a baseline sensitivity of 53.8% (CI 35.4–71.4%), baseline specificity 99.7% (CI 98.4–100%) and overall accuracy of 80% (95% CI 0.68–0.91); the AFIAS COVID-19 Ag kit, baseline sensitivity of 86.4% (CI 75.0–93.9%), baseline specificity 98.3% (CI 97.1–99.1%) and overall accuracy of 95.3% (95% CI 0.92– 0.99). In both tests, some samples showed very low viral load and negative Ag-RDT. This disagreement may reflect the positive inability of Ag-RDTs of detecting antigen in late phase of infection. Among all cases with positive molecular test and negative antigen test, none showed viral loads > 106 copies/mL. Finally, we found one false Ag-RDTs negative result (low cycle thresholds; 9 × 105 copies/mL). Our results suggest that both Ag-RDTs showed good performances in detection of high viral load samples, making it a feasible and effective tool for mass screening in actively infected children