Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userNew CAST Limit on the Axion-Photon Interaction
90
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
During 2003--2015, the CERN Axion Solar Telescope (CAST) has searched for $atogamma$ conversion in the 9 T magnetic field of a refurbished LHC test magnet that can be directed toward the Sun. In its final phase of solar axion searches (2013--2015), CAST has returned to evacuated magnet pipes, which is optimal for small axion masses. The absence of a significant signal above background provides a world leading limit of $g_{agamma} < 0.66 times 10^{-10} {rm GeV}^{-1}$ (95% C.L.) on the axion-photon coupling strength for $m_a lesssim 0.02$ eV. Compared with the first vacuum phase (2003--2004), the sensitivity was vastly increased with low-background x-ray detectors and a new x-ray telescope. These innovations also serve as pathfinders for a possible next-generation axion helioscope.
rate research
Read More
The CERN Axion Solar Telescope (CAST) searches for $atogamma$ conversion in the 9 T magnetic field of a refurbished LHC test magnet that can be directed toward the Sun. Two parallel magnet bores can be filled with helium of adjustable pressure to match the X-ray refractive mass $m_gamma$ to the axion search mass $m_a$. After the vacuum phase (2003--2004), which is optimal for $m_alesssim0.02$ eV, we used $^4$He in 2005--2007 to cover the mass range of 0.02--0.39 eV and $^3$He in 2009--2011 to scan from 0.39--1.17 eV. After improving the detectors and shielding, we returned to $^4$He in 2012 to investigate a narrow $m_a$ range around 0.2 eV (candidate setting of our earlier search) and 0.39--0.42 eV, the upper axion mass range reachable with $^4$He, to cross the axion line for the KSVZ model. We have improved the limit on the axion-photon coupling to $g_{agamma}< 1.47times10^{-10} {rm GeV}^{-1}$ (95% C.L.), depending on the pressure settings. Since 2013, we have returned to vacuum and aim for a significant increase in sensitivity.
During 2014 the PVLAS experiment has started data taking with a new apparatus installed at the INFN Section of Ferrara, Italy. The main target of the experiment is the observation of magnetic birefringence of vacuum. According to QED, the ellipticity generated by the magnetic birefringence of vacuum in the experimental apparatus is expected to be $psi^{rm(QED)} approx 5times10^{-11}$. No ellipticity signal is present so far with a noise floor $psi^{rm(noise)} approx 2.5times10^{-9}$ after 210 hours of data taking. The resulting ellipticity limit provides the best model independent upper limit on the coupling of axions to $gammagamma$ for axion masses above $10^{-3}$eV.
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 $^{4}{rm He}$ data taking as well as the system upgrades that have been operated in the last year in order to adapt the experiment for the $^{3}{rm He}$ data taking. Expected sensitivities on the coupling constant of axions to photons will be given for the recent $^{3}{rm He}$ run just started in March 2008.
We present the supernova constraints on an axion-photon-dark photon coupling, which can be the leading coupling to dark sector models and can also lead to dramatic changes to axion cosmology. We show that the supernova bound on this coupling has two unusual features. One occurs because the scattering that leads to the trapping regime converts axions and dark photons into each other. Thus, if one of the two new particles is sufficiently massive, both production and scattering become suppressed and the bounds from bulk emission and trapped (area) emission both weaken exponentially and do not intersect. The other unusual feature occurs because for light dark photons, longitudinal modes couple more weakly than transverse modes do. Since the longitudinal mode is more weakly coupled, it can still cause excessive cooling even if the transverse mode is trapped. Thus, the supernova constraints for massive dark photons look like two independent supernova bounds super-imposed on top of each other.
Physics beyond the Standard Model predicts the possible existence of new particles that can be searched at the low energy frontier in the sub-eV range. The OSQAR photon regeneration experiment looks for Light Shining through a Wall from the quantum oscillation of optical photons into Weakly Interacting Sub-eV Particles, such as axion or Axion-Like Particles (ALPs), in a 9 T transverse magnetic field over the unprecedented length of $2 times 14.3$ m. In 2014, this experiment has been run with an outstanding sensitivity, using an 18.5 W continuous wave laser emitting in the green at the single wavelength of 532 nm. No regenerated photons have been detected after the wall, pushing the limits for the existence of axions and ALPs down to an unprecedented level for such a type of laboratory experiment. The di-photon couplings of possible pseudo-scalar and scalar ALPs can be constrained in the nearly massless limit to be less than $3.5cdot 10^{-8}$ GeV$^{-1}$ and $3.2cdot 10^{-8}$ GeV$^{-1}$, respectively, at 95% Confidence Level.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
