Tag Archives: moments

An update to the nuclear moments database

The nuclear moments database is sponsored and hosted by the IAEA Nuclear Data Section.
See the latest official release here:
http://www-nds.iaea.org/nuclearmoments

This is a major update with cutoff date 30.06.2016. The next is scheduled for 30.09.2016.

On the parallel, on the development server (always on beta status) http://data.magneticmoments.info
a new database is being tested that additionally includes nuclear charge radii and nuclear masses (in fact mass excess values).
This database is currently in sync with the IAEA servers, but will eventually branch out (early next year).

My recommendation is to follow the official releases on IAEA web if you want to use it in a paper (please cite the database using the citations listed in the server). If you can’t wait for the official release, try the development server, where more features are and will be available as the site expands.

Typos, comments or missing values? PLEASE let me know about it (thanks in advance!)
The blog is also there for more resources http://magneticmoments.info/wp

An update of the nuclear moments update: masses and charge radii

For those of you who are following my blog or twitter feed, what I am about to say is not quite new. I have already made a comment a couple of weeks ago regarding the last update of the database I administer. The database contains non-evaluated, experimentally deduced values of nuclear magnetic dipole and electric quadrupole moments. The official release of the database is hosted on IAEA servers and they are responsible for the dissemination of the information included to the world’s nuclear community. However, I keep a test server available for updates and testing new ideas before they appear on the IAEA’s website. This URL is http://magneticmoments.info/data

As I said earlier, a couple of weeks ago I have managed to find the time and upgrade the database with two important observables that people have requested in the recent past. The first one is masses, while the second one is nuclear charge radii. The former is listed in each isotope selected in the database in the form of mass excess Δm (=mass-A). Please notice I do not provide the whole table maintained by the Chinese colleagues (latest AME2012). Rather, I use it as an associate value to the spectroscopic values included when an isotope is selected.

The nuclear charge radii on the other hand is a new addition to the database and I intend to keep updating regardless the official releases (in print format) by IAEA or any other source. The radii are important structure information and as such they will be treated with extra care during each upgrade.

Besides these two extensive updates, lifetimes, spins and parities are slowly being synced with the evaluated data existing in the ENSDF.

You spot a problem or have something to say about the database, please let me know.

An online database of nuclear moments

The following is a little blog piece I wrote for Science2.0 site.
Here is the direct link to it

If you are into Nuclear Physics there is very good chance you know about nuclear electromagnetic moments. Actually, nuclear electromagnetic moments has been the field of my specialty from the beginning of my scientific career. This is also why my blog in science20.com was named “Moment Zero” and not because there was some zero-time singularity I broke into writing about scientific stuff (not that I have been very active in here either!). The term nuclear electromagnetic moments 90% of the time refer to the magnetic dipole and the electric quadrupole moment. Each of these physics observables have something important to say about the nucleus.

The nuclear magnetic dipole moment, μ, is a unique case of a quantum operator describing the nuclear magnetism in terms of the spin of the state the nucleus resides in. Its uniqueness relies on the fact that it is extremely sensitive on the proton-neutron content -and competition- of the wave function. No other observable can really say anything about individual nucleons participating (and how much each of them contributes to) in the wave function. Thus measuring magnetic dipoles moments we can determine the wave function of a nuclear state in terms of the single-particle degrees of freedom.

On the other hand, the electric quadrupole moment, Q, is a quantity that reveals the shape of the nucleus. Most often the nucleus can be a spheroid or an ellipsoid. Ideal spherical nuclei, such as those considered for nuclei with spin/parity 0+, present a zero electric quadrupole moment. If the shape of the nucleus is elongated along the rotation of the axis, similarly to an upside standing rugby ball, Q has a positive value (prolate shape), while in the opposite case of a lay-down egg shaped nucleus (oblate shape) Q is negative. The relationship between the value of the quadrupole moment and the shape of the nucleus is so strong that very often it is only necessary to determine the sign of the quadrupole moment, and not the value itself, to have a nice physics result.

For either type of nuclear moment, several techniques have been developed over the years, with the best known to the wider physics audience being the Nuclear Magnetic Resonance technique (developed by I.I. Rabi who got the Nobel for it in 1944). Lots of experimental data have been accumulated and with the revolution of radioactive beams taking over the nuclear physics community in the past 15 years a new blooming of phenomena is developing fast. Experimental data had been tabulated already since before WWII and more than ten compilations (with some very important ones) have been put together to offer the community a concise way of finding information. However, there has been no online presence of recent data, despite the big efforts by IAEA and other organizations to develop online tools.

Very recently, an effort started 7 years ago in the University of Athens, resulted in the first online -we claim the fullest and most up-to-date- database with nuclear electromagnetic moments. The database was hosted on a private server (http://magneticmoments.info) for a few year and will continue, however, for the time being this URL is redirecting visitors to the IAEA site where the database is currently hosted. The Nuclear Data Section of IAEA has come into an agreement to host the database with a cutoff date Nov 2015 (this means there is no more major update is in the works and appear online by the end of this year).
So, if you are into experimental data, and especially nuclear physics EM moments, stop by and find little treasures. There is also an accompanying blog (http://magneticmoments.info/wp) where fellow researchers can comment, offer valuable insights or even contribute their data.

You are welcome to visit!

PS A related publication was very recently accepted for publication in NIM A. Please, cite it if you are about to use any of the data in the database in your own work doi: 10.1016/j.nima.2015.10.096

A critical update of the nuclear EM moments database

Some of you know about my efforts to put together a database containing experimental data of nuclear electromagnetic (EM) moments. I am not going to go into details about what a nuclear moments is; all Nuclear Physics textbooks have extended information on them and why they are useful for nuclear structure.

 I have to clarify that I have stood on the shoulders of giants: Several researchers have tabulated experimental data, both on magnetic dipole and electric quadrupole moments, and made them available in print. Already since my PhD years I found myself struggling to find the proper info out of printed copies of those compilations (PDF were very scarce 10-15 years ago). The most recent compilation has been made available by Nick Stone, a colossal work indeed. Still, printed matter is all you can get.

In 2007 I decided I should take over the very hard task to import the existing compilations into a modern database scheme, check the data and update them frequently, as more and more papers were published. With the help of two students, Kostas Stamou and Thanasis Psaltis, both pursuing doctoral studies as we speak, I managed to have a first version in 2009. Lots of things had still to be done from that point. Frequent updates are considered THE top and most important priority in the philosophy behind the database.

Yesterday, I have completed a major update, past due already from July, however, this one was accompanied by a vast cleanup of citation data, references and errors in all kind of things. The database has currently 5352 entries for 1205 isotopes and each single one of them has been checked for integrity. Nevertheless, I can not really brag about this, as experience has shown me in the past that there is always a good experimental error associated to such works. So, please judge me lightly if you spot something missing. And PLEASE LET ME KNOW.

The database can be found here:

http://magneticmoments.info

Version is dated: 10.09.2015 and includes all data up to Feb 2014.

I hope you find it useful.