Superconducting Superstructure for the TESLA Collider

We discuss the new layout of a cavity chain (superstructure) allowing, we hope, significant cost reduction of the RF system of both linacs of the TESLA linear collider. The proposed scheme increases the fill factor and thus makes an effective gradient of an accelerator higher. We present mainly computations we have performed up to now and which encouraged us to order the copper model of the scheme, still keeping in mind that experiments with a beam will be necessary to prove if the proposed solution can be used for the acceleration.Comment: 11 page

Vitamin D status and risk of rheumatoid arthritis: systematic review and meta-analysis

Background Vitamin D is important for immunomodulation and may play a role in autoimmune diseases. Studies have reported a high prevalence of vitamin D deficiency in rheumatoid arthritis (RA) patients, and vitamin D status, assessed by circulating 25-hydroxyvitamin D [25(OH)D] concentration, is inversely associated with RA disease activity. However, it is unclear whether vitamin D deficiency increases the risk of later developing RA. We conducted a systematic review and meta-analysis of pre-diagnostic 25(OH)D concentrations and risk of RA. Methods Medline and Embase databases were searched in December 2021 using various keywords for ‘vitamin D’, ‘rheumatoid arthritis’, and ‘prospective study’. Publications identified from the search were screened for eligibility, studies were excluded if vitamin D status was measured at or after RA diagnosis, and data were extracted from relevant articles. Bayesian meta-analysis was used to estimate the summary relative risk (RR) and 95% credible interval (CrI) for risk of RA in relation to circulating 25(OH)D concentrations, as well as the between-study heterogeneity. Results The search strategy yielded 908 records, of which 4 publications reporting on 7 studies, involving a total of 15,604 participants and 1049 incident RA cases, were included in the meta-analysis. There was no suggestion of an association between 25(OH)D concentration and subsequent risk of RA. The pooled RR per 25 nmol/L increment in 25(OH)D was 0.96 (95% CrI 0.82–1.13; I2 = 52%). No associations were evident in men (RR = 1.02, 95% CrI 0.65–1.61; I2 = 77%, 2 studies) or women (RR = 0.94, 95% CrI 0.73–1.22; I2 = 71%, 4 studies). Conclusions This systematic review and meta-analysis did not identify evidence of an association between 25(OH)D and RA risk, but there was notable between-study heterogeneity and a lack of precision. Investigations in large-scale prospective studies with long follow-up or suitably designed Mendelian randomisation studies with consideration of potential non-linear relationships are needed to determine whether vitamin D is involved in RA aetiology

Progress on a spherical TPC for low energy neutrino detection

The new concept of the spherical TPC aims at relatively large target masses with low threshold and background, keeping an extremely simple and robust operation. Such a device would open the way to detect the neutrino-nucleus interaction, which, although a standard process, remains undetected due to the low energy of the neutrino-induced nuclear recoils. The progress in the development of the fist 1 m$^3$ prototype at Saclay is presented. Other physics goals of such a device could include supernova detection, low energy neutrino oscillations and study of non-standard properties of the neutrino, among others.Comment: 3 pages, talk given at the 9th Workshop on Topics in Astroparticle and Underground Physics, Zaragoza, September 10-1

CAST microbulk micromegas in the Canfranc Underground Laboratory

During the last taking data campaigns of the CAST experiment, the micromegas detectors have achieved background levels of $\approx 5 \times 10^{-6}$keV$^{-1}$cm$^{-2}$s$^{-1}$ between 2 and 9 keV. This performance has been possible thanks to the introduction of the microbulk technology, the implementation of a shielding and the development of discrimination algorithms. It has motivated new studies towards a deeper understanding of CAST detectors background. One of the working lines includes the construction of a replica of the set-up used in CAST by micromegas detectors and its installation in the Canfranc Underground Laboratory. Thanks to the comparison between the performance of the detectors underground and at surface, shielding upgrades, etc, different contributions to the detectors background have been evaluated. In particular, an upper limit $< 2 \times 10^{-7}$keV$^{-1}$cm$^{-2}$s$^{-1}$ for the intrinsic background of the detector has been obtained. This work means a first evaluation of the potential of the newest micromegas technology in an underground laboratory, the most suitable environment for Rare Event Searches.Comment: 6 pages, 8 figures. To appear in the proceedings of the 2nd International Conference on Technology and Instrumentation for Particle Physics (TIPP 2011

X-ray detection with Micromegas with background levels below 10−6^{-6} keV−1^{-1}cm−2^{-2}s−1^{-1}

Micromegas detectors are an optimum technological choice for the detection of low energy x-rays. The low background techniques applied to these detectors yielded remarkable background reductions over the years, being the CAST experiment beneficiary of these developments. In this document we report on the latest upgrades towards further background reductions and better understanding of the detectors' response. The upgrades encompass the readout electronics, a new detector design and the implementation of a more efficient cosmic muon veto system. Background levels below 10$^{-6}$keV$^{-1}$cm$^{-2}$s$^{-1}$ have been obtained at sea level for the first time, demonstrating the feasibility of the expectations posed by IAXO, the next generation axion helioscope. Some results obtained with a set of measurements conducted in the x-ray beam of the CAST Detector Laboratory will be also presented and discussed

Characterization of microbulk detectors in argon- and neon-based mixtures

A recent Micromegas manufacturing technique, so called Microbulk, has been developed, improving the uniformity and stability of this kind of detectors. Excellent energy resolutions have been obtained, reaching values as low as 11% FWHM at 5.9 keV in Ar+5%iC4H10. This detector has other advantages like its flexible structure, low material budget and high radio-purity. Two microbulk detectors with gaps of 50 and 25 um have been characterized in argon- and neon-based mixtures with ethane, isobutane and cyclohexane. The results will be presented and discussed. The gain curves have been fitted to the Rose-Korff gain model and dependences of the electron mean free path and the threshold energy for ionization have been obtained. The possible relation between these two parameters and the energy resolution will be also discussed.Comment: Submitted to the Journal of Instrumentatio

Lowering the background level and the energy threshold of Micromegas x-ray detectors for axion searches

Axion helioscopes search for solar axions by their conversion in x-rays in the presence of high magnetic fields. The use of low background x-ray detectors is an essential component contributing to the sensitivity of these searches. In this work, we review the recent advances on Micromegas detectors used in the CERN Axion Solar Telescope (CAST) and proposed for the future International Axion Observatory (IAXO). The actual setup in CAST has achieved background levels below 10$^{-6}$ keV$^{-1}$ cm$^{-2}$ s$^{-1}$, a factor 100 lower than the first generation of Micromegas detectors. This reduction is based on active and passive shielding techniques, the selection of radiopure materials, offline discrimination techniques and the high granularity of the readout. We describe in detail the background model of the detector, based on its operation at CAST site and at the Canfranc Underground Laboratory (LSC), as well as on Geant4 simulations. The best levels currently achieved at LSC are low than 10$^{-7}$ keV$^{-1}$ cm$^{-2}$ s$^{-1}$ and show good prospects for the application of this technology in IAXO. Finally, we present some ideas and results for reducing the energy threshold of these detectors below 1 keV, using high-transparent windows, autotrigger electronics and studying the cluster shape at different energies. As a high flux of axion-like-particles is expected in this energy range, a sub-keV threshold detector could enlarge the physics case of axion helioscopes.Comment: Proceedings of 3rd International Conference on Technology and Instrumentation in Particle Physics (TIPP 2014

The Study of TeV Variability and Duty Cycle of Mrk 421 from 3 Years of Observations with the Milagro Observatory

TeV flaring activity with time scales as short as tens of minutes and an orphan TeV flare have been observed from the blazar Markarian 421 (Mrk 421). The TeV emission from Mrk 421 is believed to be produced by leptonic synchrotron self-Compton (SSC) emission. In this scenario, correlations between the X-ray and the TeV fluxes are expected, TeV orphan flares are hardly explained and the activity (measured as duty cycle) of the source at TeV energies is expected to be equal or less than that observed in X-rays if only SSC is considered. To estimate the TeV duty cycle of Mrk 421 and to establish limits on its variability at different time scales, we continuously observed Mrk 421 with the Milagro observatory. Mrk 421 was detected by Milagro with a statistical significance of 7.1 standard deviations between 2005 September 21 and 2008 March 15. The observed spectrum is consistent with previous observations by VERITAS. We estimate the duty cycle of Mrk 421 for energies above 1 TeV for different hypothesis of the baseline flux and for different flare selections and we compare our results with the X-ray duty cycle estimated by Resconi et al. 2009. The robustness of the results is discussed.Comment: 27 pages, 6 figures, ApJ accepte

Preventing type 2 diabetes mellitus in Qatar by reducing obesity, smoking, and physical inactivity: mathematical modeling analyses.

BACKGROUND: The aim of this study was to estimate the impact of reducing the prevalence of obesity, smoking, and physical inactivity, and introducing physical activity as an explicit intervention, on the burden of type 2 diabetes mellitus (T2DM), using Qatar as an example. METHODS: A population-level mathematical model was adapted and expanded. The model was stratified by sex, age group, risk factor status, T2DM status, and intervention status, and parameterized by nationally representative data. Modeled interventions were introduced in 2016, reached targeted level by 2031, and then maintained up to 2050. Diverse intervention scenarios were assessed and compared with a counter-factual no intervention baseline scenario. RESULTS: T2DM prevalence increased from 16.7% in 2016 to 24.0% in 2050 in the baseline scenario. By 2050, through halting the rise or reducing obesity prevalence by 10-50%, T2DM prevalence was reduced by 7.8-33.7%, incidence by 8.4-38.9%, and related deaths by 2.1-13.2%. For smoking, through halting the rise or reducing smoking prevalence by 10-50%, T2DM prevalence was reduced by 0.5-2.8%, incidence by 0.5-3.2%, and related deaths by 0.1-0.7%. For physical inactivity, through halting the rise or reducing physical inactivity prevalence by 10-50%, T2DM prevalence was reduced by 0.5-6.9%, incidence by 0.5-7.9%, and related deaths by 0.2-2.8%. Introduction of physical activity with varying intensity at 25% coverage reduced T2DM prevalence by 3.3-9.2%, incidence by 4.2-11.5%, and related deaths by 1.9-5.2%. CONCLUSIONS: Major reductions in T2DM incidence could be accomplished by reducing obesity, while modest reductions could be accomplished by reducing smoking and physical inactivity, or by introducing physical activity as an intervention