arXiv subjects
Publications and source records attributed to Sheau-shi Pan.
We indicate the progress of experimental gravity, present an outlook in this field, and summarise the Observational/Experimental Parallel Session together with a related plenary talk on gravitational waves of the 2nd LeCosPA Symposium.
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 vacuum dichroism in a magnetic field. Motivated to measure the QED vacuum 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 give a brief historical account of planet hunting and dark matter evidence. We then review our 3.5 m Fabry-Perot interferometer together with our results of measuring vacuum dichroism and gaseous Cotton-Mouton effects. Our first results give (-0.2 $\pm$ 2.8) $\times$ 10$^{-13}$ rad/pass, at 2.3 T with 18,700 passes through a 0.6 m long magnet, for vacuum dichroism measurement. We are upgrading our interferometer to 7 m arm-length with a new 1.8 m 2.3 T permanent magnet capable of rotation up to 13 cycles per second. We aim at 10 nrad/Hz$^{1/2}$ optical sensitivity with 532 nm cavity finesse around 100,000. When achieved, vacuum dichroism would be measured to 8.6 $\times$ 10$^{-17}$ rad/pass in about 50 days, and QED birefringence would be measured to 28 %.
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 Fabry-Perot interferometer together with our results of measuring Cotton-Mouton effects of gases. We are uprading our interferometer to 7 m armlength with a new 1.8 m 2.3 T permanent magnet capable of rotation up to 13 cycles per second. We will use 532 nm Nd:YAG laser as light source with cavity finesse around 100,000, and aim at 10 nrad/Hz^{1/2} optical sensitivity. With all these achieved and the upgrading of vacuum, QED birefringence would be measured to 28% in about 50 days. Along the way, we should be able to improve on the dichroism detection significantly.
Experiments for vacuum birefringence and vacuum dichroism have been set up with high-finesse high magnetic experimental apparatuses, which seem to be ideal for small gaseous Cotton-Mouton effect (CME) measurements. PVLAS Collaboration has measured CMEs in krypton, xenon and neon at the wavelength of 1064 nm. In this Letter, we report on our measurement of CMEs in nitrogen, oxygen, carbon dioxide, argon, and krypton at the same wavelength in a magnetic field B = 2.3 T at pressure P = 0.5-300 Torr and temperature T = 295-298 K. Our results agree with the PVLAS results in the common cases.