Search Menu
Photonics Media Photonics Marketplace Photonics Spectra BioPhotonics EuroPhotonics Vision Spectra Photonics Showcase Photonics ProdSpec Photonics Handbook

Lab Experiment Probes Photon Charge

Facebook Twitter LinkedIn Email Comments
Researchers at Brookhaven National Laboratory in Upton, N.Y., have devised a new apparatus for measuring the upper limit on the charge of the photon. The approach, which was described in the Jan. 1 issue of Physical Review D, has yielded results an order of magnitude better than previous laboratory experiments, and it promises a sensitivity of 10-21 e with minor improvements.

Variations in the time of flight of radio-frequency emissions from pulsars due to dispersion in the intergalactic magnetic field have produced an upper limit on photon charge of 5 x 10-30 e, but laboratory tests had done no better than 10-16 e. The new technique monitors the deflection of a 1-mW HeNe laser beam by a modulated magnetic field and has obtained an upper limit of 8.5 x 10-17 e with a prototype apparatus. The team suggests improvements in the apparatus to boost sensitivity, such as increasing the optical path length and suppressing sources of noise with better isolation of the magnet.

Photonics Spectra
Mar 2003
A quantum of electromagnetic energy of a single mode; i.e., a single wavelength, direction and polarization. As a unit of energy, each photon equals hn, h being Planck's constant and n, the frequency of the propagating electromagnetic wave. The momentum of the photon in the direction of propagation is hn/c, c being the speed of light.
As We Go To PressBreaking Newschargedispersion in the intergalactic magnetic fieldlaboratory experimentsphotonPresstime Bulletinpulsarsradio-frequency emissionsupper limit

view all
Search more than 4000 manufacturers and suppliers of photonics products and services worldwide:

back to top
Facebook Twitter Instagram LinkedIn YouTube RSS
©2021 Photonics Media, 100 West St., Pittsfield, MA, 01201 USA, [email protected]

Photonics Media, Laurin Publishing
x Subscribe to Photonics Spectra magazine - FREE!
We use cookies to improve user experience and analyze our website traffic as stated in our Privacy Policy. By using this website, you agree to the use of cookies unless you have disabled them.