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Data for nuclear astrophysics
Data for nuclear astrophysics
We're involved with in a number of projects which collate data from nuclear experiments in order to provide thermonuclear reaction rates for use in stellar models. There's always work to be done in this area so if you're interested then please get in touch.
Current evaluation projects which are outstanding include:
Reanalysis of alpha-particle resonance scattering data from Ne20 to find out why certain states in Mg24 aren't observed. This is connected to the C12+C12 fusion reaction in massive stars.
Systematics of widths derived from mirrored systems - the (d,p) reaction is often used as a mirror proxy for proton-capture reactions. The systematic uncertainties introduced as part of this process are not well understood. A survey of the available data should let us better estimate the systematic uncertainties.
Photoabsorption strengths - the historical photoneutron data have problems, likely due to the neutron multiplicity sorted. We're leading a couple of projects, one trying to pin down the problems with historical photoneutron data, and the other trying to develop a model-independent calibration standard for photoneutron reactions.
Pollution in globular clusters - Some globular clusters show odd abundance patterns which are likely due to pollution from a previous generation of stars. We need to understand some key nuclear reactions to identify the nature of the polluting site in these globular clusters.
Rate Evaluations
Rate Evaluations
Rate evaluations either independently or as part of an experiment study on which I've worked include:
New measurement of the Ec.m.=323 keV resonance in the 19F(p,γ)20Ne reaction
M. Williams, P. Adsley, B. Davids, U. Greife, D. Hutcheon, J. Karpesky, A. Lennarz, M. Lovely, and C. Ruiz
Phys. Rev. C 103, 055805
Reevaluation of the 22Ne(α,γ)26Mg and 22Ne(α,n)25Mg reaction rates
Philip Adsley, Umberto Battino, Andreas Best, Antonio Caciolli, Alessandra Guglielmetti, Gianluca Imbriani, Heshani Jayatissa, Marco La Cognata, Livio Lamia, Eliana Masha, Cristian Massimi, Sara Palmerini, Ashley Tattersall, and Raphael Hirschi
Phys. Rev. C 103, 015805
Evaluation of experimental constraints on the 44Ti(α,p)47V reaction cross section relevant for supernovae
K. A. Chipps, P. Adsley, M. Couder, W. R. Hix, Z. Meisel, and Konrad Schmidt
Phys. Rev. C 102, 035806
Constraints on key 17O(α,γ)21Ne resonances and impact on the weak s process
M. Williams, A. M. Laird, A. Choplin, P. Adsley, B. Davids, U. Greife, K. Hudson, D. Hutcheon, A. Lennarz, and C. Ruiz
Phys. Rev. C 105, 065805
Rate Libraries
Rate Libraries
There are a number of different reaction-rate libraries. Some of my favourites with some guidance on them are listed below.
REACLIB - https://reaclib.jinaweb.org/
REACLIB is probably the most complete library of rates. It doesn't seem to be updated with new rates that regularly and getting uncertainties is frequently a problem.
STARLIB - https://starlib.github.io/Rate-Library/
This is a similar database to REACLIB but it includes uncertainties so I generally prefer it. There are a few bugs in some of the rates which are worth keeping an eye out for, especially if you're using the web server to generate new rates from your own nuclear physics inputs. The web server isn't quite needed since Richard Longland has made the RatesMC code for calculating rates from nuclear-physics inputs available...
Here: RatesMC - https://github.com/rlongland/RatesMC
This is a Monte-Carlo code that allows nuclear physics inputs to be used to generate reaction rates with meaningful uncertainties. I am working on some updates to this code, notably checking the integration routines to make sure that they are working properly when computing the reaction rates. This is my preferred option for rate evaluations if you're doing one yourself since the code is well characterised and is used in other evaluations as well (so the differences are not due to calculations but based on nuclear physics data, hopefully).
NACRE/BRUSLIB - http://www.astro.ulb.ac.be/pmwiki/IAA/Databases
BRUSLIB includes various collections of useful nuclear data like masses, E1 strengths etc. It also includes NACRE II which is an evaluation of important rates on stable nuclei of less than mass 16. Note that the original NACRE database is more than 20 years old and unless you have a very good reason, comparisons to the original NACRE rates is generally not required. Especially for a number of important reactions (I'm looking at you, 22Ne+α!) the nuclear data which went into the evaluations has been extensively revised and so the original NACRE rates are extremely outdated and require extreme caution.
ChANUREPS - http://141.2.212.122/chanureps/
This is a repository of rates maintained by Umberto Battino from the University of Hull. The good thing about this repository is that when people upload rates (as you should!) they also give a brief description of the rate and can list useful bits of information which may not easily come out from other repositories.
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