Enhanced Transmission in Rolled-up Hyperlenses utilizing Fabry-Pe\'rot Resonances

We experimentally demonstrate that the transmission though rolled-up metal/semiconductor hyperlenses can be enhanced at desired frequencies utilizing Fabry-P\'erot resonances. By means of finite difference time domain simulations we prove that hyperlensing occurs at frequencies of high transmission.Comment: 3 pages, 3 figure

The T-REX projec t: Micromegas for rare event searches

Yıldız, Şükrü C. (Dogus Author) -- This paper was firstyly submitted to 2nd International Conference on Particle Physics in Memoriam Engin Arik and Her Colleagues.The T-REX project aims at developing novel readout techniques for Time Projection Chambers for experiments searching for Rare Events. The Micromegas detectors are a good option, because of their good performance regarding low background levels, energy and time resolution, gain and stability of operation. In the present we will shortly refer to two particular cases, on one hand their performance in the CAST experiment and on the other the studies carried out within NEXT, a neutrinoless double-beta decay experiment

Status and perspectives of the CAST experiment

Arık, Metin (Dogus Author) -- The conference paper was firstly submitted to 12th International Conference on Topics in Astroparticle and Underground Physics.The CERN Axion Solar Telescope (CAST) is currently the most sensitive axion helioscope designed to search for axions produced by the Primakoff process in the solar core. CAST is using a Large Hadron Collider (LHC) test magnet where axions could be converted into X-rays with energies up to 10 keV. During the phase I, the experiment operated with vacuum inside the magnet bores and covered axion masses up to 0.02 eV. In the phase II, the magnet bores were filled with a buffer gas (first 4He and later 3He) at various densities in order to extend the sensitivity to higher axion masses (up to f .18 eV). The phase II data taking was completed in 2011. So far, no evidence of axion signal has been found and CAST set the most restrictive experimental limit on the axion-photon coupling constant over a broad range of axion masses. The latest CAST results with 3He data in the mass range 0.39 eV < m a < 0.64 eV will be presented

Gain in Three-Dimensional Metamaterials utilizing Semiconductor Quantum Structures

We demonstrate gain in a three-dimensional metal/semiconductor metamaterial by the integration of optically active semiconductor quantum structures. The rolling-up of a metallic structure on top of strained semiconductor layers containing a quantum well allows us to achieve a three-dimensional superlattice consisting of alternating layers of lossy metallic and amplifying gain material. We show that the transmission through the superlattice can be enhanced by exciting the quantum well optically under both pulsed or continuous wave excitation. This points out that our structures can be used as a starting point for arbitrary three-dimensional metamaterials including gain

Performance of micromegas detectors in the CAST Experiment

Yıldız, Şükrü C. (Dogus Author) -- This paper was firstly submitted to 2nd International Conference on Particle Physics in Memoriam Engin Arik and Her Colleagues.CERN Axion Solar Telescope (CAST) experiment is searching for axions coming from the Sun. Inside transverse magnetic fields, axions can be converted into X-rays, which can be detected by X-ray detectors. The expected energy of the signal in CAST is in the 1-10 keV range. Low noise and low background detectors are necessary to increase the sensitivity of the experiment. Micro Mesh Gaseous Structure (micromegas) detectors have been used in CAST since the beginning, providing good energy and spatial resolution for CAST's needs. CAST has been intensely studying micromegas detectors to develop new technologies. Initially, CAST detectors consisted of a micromegas, a Time Projection Chamber (TPC) and a Charged Couple Device (CCD), however the improvements in micromegas technologies encouraged CAST to replace the TPC with 2 new micromegas detectors. In some periods during CAST run, ultra low background has been observed in one of the micromegas detectors and it is being investigated through simulations and laboratory tests carried out at Canfranc Underground Laboratory. If this low background is indeed not a systematic effect, it can open new possibilities on rare event searches

Latest results and prospects of the CERN Axion Solar Telescope

Çetin, Serkant Ali (Dogus Author) -- Ezer, C. (Dogus Author) -- Yıldız, Süleyman Cenk (Dogus Author)The CERN Axion Solar Telescope (CAST) experiment searches for axions from the Sun converted into few keV photons via the inverse Primakoff effect in the high magnetic field of a superconducting Large Hadron Collider (LHC) decommissioned test magnet. After results obtained with vacuum in the magnet pipes (phase I of the experiment) as well as with 4He the collaboration is now immersed in the data taking with 3He, to be finished in 2011. The status of the experiment will be presented, including a preliminary exclusion plot of the first 3He data. CAST is currently sensitive to realistic QCD axion models at the sub-eV scale, and with axion-photon couplings down to the ∼ 2 × 10-10 GeV -1, compatible with solar life limits. Future plans include revisiting vaccuum and 4He configurations with improved sensitivity, as well as possible additional search for non-standard signals from chamaleons, paraphotons or other WISPs. For the longer term, we study the feasibility of an altogether improved version of the axion helioscope concept, with a jump in sensitivity of about one order of magnitude in gaγ beyond CAST

Solar axion search with the CAST experiment

Şenel Boydağ, Fatma (Dogus Author), Çetin, Serkant Ali (Dogus Author), Hikmet, İskender (Dogus Author) -- Proceedings of the 34th International Conference in High Energy Physics : (ICHEP08) Philadelphia, Pennsylvania, July 29 - August 5, 2008.The CAST (CERN Axion Solar Telescope) experiment is searching for solar axions by their conversion into photons inside the magnet pipe of an LHC dipole. The analysis of the data recorded during the first phase of the experiment with vacuum in the magnet pipes has resulted in the most restrictive experimental limit on the coupling constant of axions to photons. In the second phase, CAST is operating with a buffer gas inside the magnet pipes in order to extent the sensitivity of the experiment to higher axion masses. We will present the first results on the 4He data taking as well as the system upgrades that have been operated in the last year in order to adapt the experiment for the 3He data taking. Expected sensitivities on the coupling constant of axions to photons will be given for the recent 3He run just started in March 2008

CAST: Recent results & future outlook

Çetin, Serkant Ali (Dogus Author) -- Ezer, Cemile (Dogus Author) -- Yıldız, Süleyman Cenk (Dogus Author) -- Conference full title: 6th Patras Workshop on Axions, WIMPs and WISPs, PATRAS 2010; Zurich; Switzerland; 5 July 2010 through 9 July 2010.The CAST (CERN Axion Solar Telescope) experiment is searching for solar axions by their conversion into photons inside the magnet pipes of an LHC dipole. The analysis of data taken so far has shown no signal above the background, thus implying an upper limit to the axion-photon coupling of ga < 0.85 × 10-10GeV -1 at 95% CL for ma < 0.02 eV/c2. Ongoing measurements, with the magnet bores filled with a buffer gas (3He), are improving the sensitivity of the experiment for higher axion masses towards 1 eV/c2. Recent results, new ideas for Axion-Like Particle (WISPs) searches with CAST in the near future and the prospects of a new generation Helioscope are presented here

New neutron detector based on Micromegas technology for ADS projects

A new neutron detector based on Micromegas technology has been developed for the measurement of the simulated neutron spectrum in the ADS project. After the presentation of simulated neutron spectra obtained in the interaction of 140 MeV protons with the spallation target inside the TRIGA core, a full description of the new detector configuration is given. The advantage of this detector compared to conventional neutron flux detectors and the results obtained with the first prototype at the CELINA 14 MeV neutron source facility at CEA-Cadarache are presented. The future developments of operational Piccolo-Micromegas for fast neutron reactors are also described

Antibiotic-loaded bone cement in prevention of periprosthetic joint infections in primary total knee arthroplasty: A register-based multicentre randomised controlled non-inferiority trial (ALBA trial)

Introduction The current evidence on the efficacy of antibiotic-loaded bone cement (ALBC) in reducing the risk of periprosthetic joint infections (PJI) after primary joint reconstruction is insufficient. In several European countries, the use of ALBC is routine practice unlike in the USA where ALBC use is not approved in low-risk patients. Therefore, we designed a double-blinded pragmatic multicentre register-based randomised controlled non-inferiority trial to investigate the effects of ALBC compared with plain bone cement in primary total knee arthroplasty (TKA). Methods and analysis A minimum of 9,172 patients undergoing full-cemented primary TKA will be recruited and equally randomised into the ALBC group and the plain bone cement group. This trial will be conducted in Norwegian hospitals that routinely perform cemented primary TKA. The primary outcome will be risk of revision surgery due to PJI at 1-year of follow-up. Secondary outcomes will be: risk of revision due to any reason including aseptic loosening at 1, 6, 10 and 20 years of follow-up; patient-related outcome measures like function, pain, satisfaction and health-related quality of life at 1, 6 and 10 years of follow-up; risk of changes in the microbial pattern and resistance profiles of organisms cultured in subsequent revisions at 1, 6, 10 and 20 years of follow-up; cost-effectiveness of routine ALBC versus plain bone cement use in primary TKA. We will use 1:1 randomisation with random permuted blocks and stratify by participating hospitals to randomise patients to receive ALBC or plain bone cement. Inclusion, randomisation and follow-up will be through the Norwegian Arthroplasty Register. Ethics and dissemination The trial was approved by the Western Norway Regional Committees on Medical and Health Research Ethics (reference number: 2019/751/REK vest) on 21 June 2019. The findings of this trial will be disseminated through peer-reviewed publications and conference presentations. Trial registration number NCT04135170.publishedVersio