相关论文: Improving ellipticity detection sensitivity for th…
The Q & A experiment, first proposed and started in 1994, provides a feasible way of exploring the quantum vacuum through the detection of vacuum birefringence effect generated by QED loop diagram and the detection of the polarization…
Motivated to measure the QED birefringence and to detect pseudoscalar-photon interaction, we started to build up the Q & A experiment (QED [Quantum Electrodynamics] and Axion experiment) in 1994. In this talk, we first review our 3.5 m…
We have built and tested a 3.5 m high-finesse Fabry-Perot prototype inteferometer with a precision ellipsometer for the QED test and axion search (Q & A) experiment. We use X-pendulum-double-pendulum suspension designs and automatic control…
A number of experiments are underway to detect vacuum birefringence and dichroism -- PVLAS, Q & A, and BMV. Recently, PVLAS experiment has observed optical rotation in vacuum by a magnetic field (vacuum dichroism). Theoretical…
The Q & A experiment, aiming at the detection of vacuum birefringence predicted by quantum electrodynamics, consists mainly of a suspended 3.5 m Fabry-Perot cavity, a rotating permanent dipole magnet and an ellipsometer. The 2.3 T magnet…
Dark matter is a focused issue in galactic evolution and cosmology. Axion is a viable particle candidate for dark matter. Its interaction with photon is an effective way to detect it, e.g., pseudoscalar-photon interaction will generate…
We propose a precise ellipsometric method for the investigation of coherent light with a small ellipticity. The main feature of this method is the use of compensators with phase delays providing the maximum accuracy of measurements for the…
Ellipse and ellipsoid fitting has been extensively researched and widely applied. Although traditional fitting methods provide accurate estimation of ellipse parameters in the low-noise case, their performance is compromised when the noise…
We suggest an experiment to observe vacuum birefringence induced by intense laser fields. A high-intensity laser pulse is focused to ultra-relativistic intensity and polarizes the vacuum which then acts like a birefringent medium. The…
The PVLAS collaboration is at present running, at the Laboratori Nazionali di Legnaro of I.N.F.N., Padova, Italy, a very sensitive optical ellipsometer capable of measuring the small rotations or ellipticities which can be acquired by a…
We propose a new algorithm for real-time detection and tracking of elliptic patterns suitable for real-world robotics applications. The method fits ellipses to each contour in the image frame and rejects ellipses that do not yield a good…
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…
We describe the principle and the status of the PVLAS experiment which is presently running at the INFN section of Ferrara, Italy, to detect the magnetic birefringence of vacuum. This is related to the QED vacuum structure and can be…
Low energy non linear QED effects in vacuum have been predicted since 1936 and have been subject of research for many decades. Two main schemes have been proposed for such a 'first' detection: measurements of ellipticity acquired by a…
The PVLAS collaboration is presently assembling a new apparatus (at the INFN section of Ferrara, Italy) to detect vacuum magnetic birefringence (VMB). VMB is related to the structure of the QED vacuum and is predicted by the…
An ellipsometer is a vital precision tool used for measuring optical parameters with wide applications in many fields, including accurate measurements in film thickness, optical constants, structural profiles, etc. However, the precise…
Due to the broad applications of elliptical models, there is a long line of research on goodness-of-fit tests for empirically validating them. However, the existing literature on this topic is generally confined to low-dimensional settings,…
In this paper we derive an exact full expression for the 2D probability distribution of the ellipticity of an object measured from data, only assuming Gaussian noise in pixel values. This is a generalisation of the probability distribution…
Three measurements that broaden the scope of the experimental investigation of quarkonia modifications in heavy ion collisions are presented. Although the current statistical precision on the first two measurements does not allow one to…
The NASA/ASI Imaging X-ray Polarimetry Explorer, which will be launched in 2021, will be the first instrument to perform spatially resolved X-ray polarimetry on several astronomical sources in the 2-8 keV energy band. These measurements are…