'Spin' is an intrinsic property of many subatomic particles - it's been likened in some ways to the 'angular momentum' of a spinning ball, - but more accurately is a mathematical 'vector' or 'property'.
After the discovery that protons are composed of three quarks and their associated 'gluons', it was assumed that the proton's spin property must be derived from the 'spin' of its constituent quarks.
A 1987 experiment at CERN (which has subsequently been replicated by other experiments) showed that this is not the case. It's now thought that the quarks only contribute between 4% and 24%.
This surprising and puzzling result was termed the “proton spin crisis”. The problem is considered one of the important unsolved problems in physics.
Source : Wikipedia
Note that the as yet unexplained anomaly also applies to the Neutron, which is also built from three quarks.
For a technical description, see The Spin Structure of the Nucleon Reports on Progress in Physics Volume 82, Number 7,at arXiv.org
Also see :and
Ideas for new topics, and suggested additions / corrections for old ones, are always welcome.
If you have skills or interests in a particular field, and have suggestions for Wikenigma, get in touch !
Or, if you'd like to become a regular contributor . . . request a login password. Registered users can edit the entire content of the site, and also create new pages.
( The 'Notes for contributors' section in the main menu has further information and guidelines etc.)
You are currently viewing an auto-translated version of Wikenigma
Please be aware that no automatic translation engines are 100% accurate, and so the auto-translated content will very probably feature errors and omissions.
Nevertheless, Wikenigma hopes that the translated content will help to attract a wider global audience.