EPJ Web of Conferences
Volume 57, 2013ICAP 2012 – 23rd International Conference on Atomic Physics
|Number of page(s)||5|
|Section||Fundamental atomic tests and precision measurements|
|Published online||30 August 2013|
Frequency metrology in quantum degenerate helium
LaserLaB VU University, Department of Physics and Astronomy, De Boelelaan 1081, 1081 HV Amsterdam, The Netherlands
We have measured the absolute frequency of the 1557-nm doubly forbidden transition between the two metastable states of helium, 2 3S1 (lifetime 8000 s) and 2 1S0 (lifetime 20 ms), with 1 kHz precision. With an Einstein coefficient of 10−7 s−1 this is one of weakest optical transitions ever measured. The measurement was performed in a Bose-Einstein condensate of 4He* as well as in a Degenerate Fermi Gas of 3He*, trapped in a crossed dipole trap. From the isotope shift we deduced the nuclear charge radius difference between the α-particle and the helion. Our value differs by 4σ with a very recent result obtained on the 2 3S → 2 3P transition.
© Owned by the authors, published by EDP Sciences, 2013
This is an Open Access article distributed under the terms of the Creative Commons Attribution License 2.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.