alpha-Capture and alpha-elastic scattering on P-nuclei to probe the Hauser-Feshbach framework
by Palumbo, Annalia, Ph.D., UNIVERSITY OF NOTRE DAME, 2009, 232 pages; 3406893

Abstract:

The thirty five neutron deficient stable nuclei known as the p-nuclei are synthesized in a series of photodisintegration reactions of the (γ,n), (γ,p) and (γ,α) type in a hot γ-flux environment.

Abundance calculations involve an extended network of about 20,000 nuclear reactions of almost 2000 nuclei. The bulk of these rates are calculated theoretically with the statistical Hauser Feshbach Model (HF Model). Of particular importance in the p-process modeling are the (γ,α) branchings.

Even though in the astrophysical environment it is photodisintegration reactions that synthesize the p-nuclei, in the laboratory it is the inverse process that is generally measured. By detailed balance, it is possible to arrive at the relevant reactions. The experimental data for α-capture reactions is scarce since at the p-process temperatures (2-3 GK), the α-particle energies are typically of a few MeV and the corresponding cross sections very small. In addition, the results show a significant deviation compared to the model predictions.

The HF cross sections are governed by transmission coefficients. These are extracted from an appropriate optical model potential (OMP). The α-nucleus potential in particular is poorly known at low energies mainly due to the lack of relevant data. The observed inconsistencies between the predicted and measured (α,γ) rates may be due to problems with this α-potential parameter.

To explore the applicability of the Hauser Feshbach model, to extend the experimental database of α-capture reactions on p-nuclei, to test the global parameterizations that currently exist, and to constrain the α-nucleus potential, the α-capture cross section of 106Cd(α,γ)110Sn and the local α-nucleus potentials of 106Cd, 118Sn, and 120,124,126,128,130 Te have been measured and extracted. The experiments have been carried out at the University of Notre Dame. The results are presented here.

 
AdviserMichael Wiescher
SchoolUNIVERSITY OF NOTRE DAME
SourceDAI/B 71-05, p. , Jun 2010
Source TypeDissertation
SubjectsAstrophysics; Nuclear Physics
Publication Number3406893
Adobe PDF Access the complete dissertation:
 

» Find an electronic copy at your library.
  Use the link below to access a full citation record of this graduate work:
  http://gateway.proquest.com/openurl%3furl_ver=Z39.88-2004%26res_dat=xri:pqdiss%26rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation%26rft_dat=xri:pqdiss:3406893
  If your library subscribes to the ProQuest Dissertations & Theses (PQDT) database, you may be entitled to a free electronic version of this graduate work. If not, you will have the option to purchase one, and access a 24 page preview for free (if available).

About ProQuest Dissertations & Theses
With over 2.3 million records, the ProQuest Dissertations & Theses (PQDT) database is the most comprehensive collection of dissertations and theses in the world. It is the database of record for graduate research.

The database includes citations of graduate works ranging from the first U.S. dissertation, accepted in 1861, to those accepted as recently as last semester. Of the 2.3 million graduate works included in the database, ProQuest offers more than 1.9 million in full text formats. Of those, over 860,000 are available in PDF format. More than 60,000 dissertations and theses are added to the database each year.

If you have questions, please feel free to visit the ProQuest Web site - http://www.proquest.com - or call ProQuest Hotline Customer Support at 1-800-521-3042.