nuclear data needs for r- process calculations bradley meyer clemson university
TRANSCRIPT
![Page 1: Nuclear Data Needs for r- Process Calculations Bradley Meyer Clemson University](https://reader030.vdocuments.mx/reader030/viewer/2022033103/56649e535503460f94b4926f/html5/thumbnails/1.jpg)
Nuclear Data Needs for r-Process Calculations
Bradley Meyer
Clemson University
![Page 2: Nuclear Data Needs for r- Process Calculations Bradley Meyer Clemson University](https://reader030.vdocuments.mx/reader030/viewer/2022033103/56649e535503460f94b4926f/html5/thumbnails/2.jpg)
Four Requirements for Meaningful Measurements for Astrophysics (The et al. 1998)
• An appropriate astrophysical model of events significant for nucleosynthesis . (“Appropriate” does not necessarily = “correct”!)
• An observable from the nucleosynthesis process, usually an abundance result that is either known or measurable.
• The dependency of the value of the observable on the value of a nuclear cross section.
• An experimental strategy for measuring that cross section, or at least of using measurable data to better calculate it.
![Page 3: Nuclear Data Needs for r- Process Calculations Bradley Meyer Clemson University](https://reader030.vdocuments.mx/reader030/viewer/2022033103/56649e535503460f94b4926f/html5/thumbnails/3.jpg)
![Page 4: Nuclear Data Needs for r- Process Calculations Bradley Meyer Clemson University](https://reader030.vdocuments.mx/reader030/viewer/2022033103/56649e535503460f94b4926f/html5/thumbnails/4.jpg)
![Page 5: Nuclear Data Needs for r- Process Calculations Bradley Meyer Clemson University](https://reader030.vdocuments.mx/reader030/viewer/2022033103/56649e535503460f94b4926f/html5/thumbnails/5.jpg)
![Page 6: Nuclear Data Needs for r- Process Calculations Bradley Meyer Clemson University](https://reader030.vdocuments.mx/reader030/viewer/2022033103/56649e535503460f94b4926f/html5/thumbnails/6.jpg)
R-Process Observables
• Production of heavy elements:– Neutron-to-seed ratio (~100)
– Dependent on nuclear reactions at T9 > 4
• Details of final abundance distribution– Peaks– Freezeout abundances—smoothing
– Dependent on nuclear reactions for T9<3
![Page 7: Nuclear Data Needs for r- Process Calculations Bradley Meyer Clemson University](https://reader030.vdocuments.mx/reader030/viewer/2022033103/56649e535503460f94b4926f/html5/thumbnails/7.jpg)
Appropriate Model? Which regime?
• Low-entropy r-process
• High-entropy r-process
• High-entropy, fast expansion r-process
![Page 8: Nuclear Data Needs for r- Process Calculations Bradley Meyer Clemson University](https://reader030.vdocuments.mx/reader030/viewer/2022033103/56649e535503460f94b4926f/html5/thumbnails/8.jpg)
Production of heavy nuclei in the first place (n/s~100)
• Depends on weak interaction physics—electron capture rates, neutrino-nucleus interaction rates
• Quasi-equilibrium: nuclear masses and partition functions
• Three-body reaction rates (α+α+α12C, α+α+n9Be and 9Be+α12C+n
• Charged-particle reactions on proton-rich isotopes for the high-entropy, fast expansion regime
![Page 9: Nuclear Data Needs for r- Process Calculations Bradley Meyer Clemson University](https://reader030.vdocuments.mx/reader030/viewer/2022033103/56649e535503460f94b4926f/html5/thumbnails/9.jpg)
Meyer and Wang (2007)
![Page 10: Nuclear Data Needs for r- Process Calculations Bradley Meyer Clemson University](https://reader030.vdocuments.mx/reader030/viewer/2022033103/56649e535503460f94b4926f/html5/thumbnails/10.jpg)
Production of 4He from n, p (T9 = 10 – 8)
ppnn
HepHHenpHnHnp 42332 ),(),(),(),(
![Page 11: Nuclear Data Needs for r- Process Calculations Bradley Meyer Clemson University](https://reader030.vdocuments.mx/reader030/viewer/2022033103/56649e535503460f94b4926f/html5/thumbnails/11.jpg)
Production of 4He from n, p (T9 < 8)
ppnn
NipCupNinNinNi 5659585756 ),(),(),(),(
Too few heavy nucleineutrons and protons don’t assemble intoalpha particles and heavier speciesmany free neutrons and protonsaround to bombard the few heavy nuclei present
![Page 12: Nuclear Data Needs for r- Process Calculations Bradley Meyer Clemson University](https://reader030.vdocuments.mx/reader030/viewer/2022033103/56649e535503460f94b4926f/html5/thumbnails/12.jpg)
Meyer and Wang (2007)
![Page 13: Nuclear Data Needs for r- Process Calculations Bradley Meyer Clemson University](https://reader030.vdocuments.mx/reader030/viewer/2022033103/56649e535503460f94b4926f/html5/thumbnails/13.jpg)
Details of the Final R-Process Abundances
• Depends on:– Nuclear masses– Neutron-capture cross sections– Beta-decay rates– Spins and partition functions– Fission yields
![Page 14: Nuclear Data Needs for r- Process Calculations Bradley Meyer Clemson University](https://reader030.vdocuments.mx/reader030/viewer/2022033103/56649e535503460f94b4926f/html5/thumbnails/14.jpg)
Reference calculation
![Page 15: Nuclear Data Needs for r- Process Calculations Bradley Meyer Clemson University](https://reader030.vdocuments.mx/reader030/viewer/2022033103/56649e535503460f94b4926f/html5/thumbnails/15.jpg)
Neutron-capture cross sections
![Page 16: Nuclear Data Needs for r- Process Calculations Bradley Meyer Clemson University](https://reader030.vdocuments.mx/reader030/viewer/2022033103/56649e535503460f94b4926f/html5/thumbnails/16.jpg)
Beta-decay rates
![Page 17: Nuclear Data Needs for r- Process Calculations Bradley Meyer Clemson University](https://reader030.vdocuments.mx/reader030/viewer/2022033103/56649e535503460f94b4926f/html5/thumbnails/17.jpg)
Spins and Partition Functions
![Page 18: Nuclear Data Needs for r- Process Calculations Bradley Meyer Clemson University](https://reader030.vdocuments.mx/reader030/viewer/2022033103/56649e535503460f94b4926f/html5/thumbnails/18.jpg)
![Page 19: Nuclear Data Needs for r- Process Calculations Bradley Meyer Clemson University](https://reader030.vdocuments.mx/reader030/viewer/2022033103/56649e535503460f94b4926f/html5/thumbnails/19.jpg)
Four Requirements for Meaningful Measurements for Astrophysics (The et al. 1998)
• An appropriate astrophysical model of events significant for nucleosynthesis . (“Appropriate” does not necessarily = “correct”!)
• An observable from the nucleosynthesis process, usually an abundance result that is either known or measurable.
• The dependency of the value of the observable on the value of a nuclear cross section or other nuclear property.
• An experimental strategy for measuring that cross section, or at least of using measurable data to better calculate it.
![Page 20: Nuclear Data Needs for r- Process Calculations Bradley Meyer Clemson University](https://reader030.vdocuments.mx/reader030/viewer/2022033103/56649e535503460f94b4926f/html5/thumbnails/20.jpg)
What is libnucnet?
• A C toolkit for storing and managing nuclear reaction network.
• Built on top of libxml (the gnome XML parser and toolkit) and gsl (the GNU scientific library).
• Released under the GNU General Public License.
![Page 21: Nuclear Data Needs for r- Process Calculations Bradley Meyer Clemson University](https://reader030.vdocuments.mx/reader030/viewer/2022033103/56649e535503460f94b4926f/html5/thumbnails/21.jpg)
History of libnucnet
• Original goal—online nucleosynthesis tool• Problem—input over the web• Solution—XML (eXtensible Markup Language)• Libxml as input and output• Libxml has powerful built-in data structures (lists,
hashes, trees, etc.)—build new nucleosynthesis code on top of libxml
• Hashes provide easy access to data—particularly useful for experimentalists
![Page 22: Nuclear Data Needs for r- Process Calculations Bradley Meyer Clemson University](https://reader030.vdocuments.mx/reader030/viewer/2022033103/56649e535503460f94b4926f/html5/thumbnails/22.jpg)
Features of libnucnet
• Intrinsically 3-d• Easily handles arbitrary nuclear network (bbn to r-
process), including (any number of) isomeric states• Reactions are handled the way humans think about
them: “c12 + he4 o16 + gamma” or “o15 n15 + positron + neutrino_e”
• Hierarchically structured• Naturally uses xml as input (allows for schemas,
stylesheets, xpath selection, etc.)• Read and validate data across the web• Allows for user-supplied screening and NSE correction
factor functions.
![Page 23: Nuclear Data Needs for r- Process Calculations Bradley Meyer Clemson University](https://reader030.vdocuments.mx/reader030/viewer/2022033103/56649e535503460f94b4926f/html5/thumbnails/23.jpg)
Structure of libnucnet
• Libnucnet__Nuc.c/h: a collection of nuclei– Libnucnet__Species: a species– Libnucnet__Nuc: a collection of species
• Libnucnet__Reac.c/h: a collection of nuclear reactions– Libnucnet__Reaction: a reaction– Libnucnet__Reac: a collection of reactions
• Libnucnet.c/h: a network and a collection of zones– Libnucnet__Net: a Libnucnet__Nuc + Libnucnet__Reac– Libnucnet__Zone: a physical zone– Libnucnet: a network plus a collection of zones
![Page 24: Nuclear Data Needs for r- Process Calculations Bradley Meyer Clemson University](https://reader030.vdocuments.mx/reader030/viewer/2022033103/56649e535503460f94b4926f/html5/thumbnails/24.jpg)
XML Data for the nuclear collection<nuclear_data> <!--n--> <nuclide> <z>0</z> <a>1</a> <source>Tuli (2000)</source> <mass>8.071</mass> <spin>0.5</spin> <partf_table> <point> <t9>0.01</t9> <log10_partf>0</log10_partf> </point> <point> <t9>0.15</t9> <log10_partf>0</log10_partf> </point> </partf_table> </nuclide>…</nuclear_data>
![Page 25: Nuclear Data Needs for r- Process Calculations Bradley Meyer Clemson University](https://reader030.vdocuments.mx/reader030/viewer/2022033103/56649e535503460f94b4926f/html5/thumbnails/25.jpg)
XML Data for the nuclear collection (with states)
<!--al26--> <nuclide> <z>13</z> <a>26</a> <states> <state id="g"> <source>Tuli (2000) + Gupta and Meyer (2001)</source> <mass>-12.21</mass> <spin>5</spin> <partf_table> ... </partf_table> </state> <state id="m"> <source>Tuli (2000) + Gupta and Meyer (2001)</source> <mass>-11.982</mass> <spin>0</spin> <partf_table> ,,, </partf_table> </state> </states> </nuclide>
![Page 26: Nuclear Data Needs for r- Process Calculations Bradley Meyer Clemson University](https://reader030.vdocuments.mx/reader030/viewer/2022033103/56649e535503460f94b4926f/html5/thumbnails/26.jpg)
XML Data for Reactions—a rate table
<reaction_data>
<!-- h1 + n to h2 + gamma -->
<reaction> <source>Smith et al. (1993)</source> <reactant>h1</reactant><reactant>n</reactant> <product>h2</product><product>gamma</product> <rate_table> <point> <t9>0.001</t9> <rate>4.6168E+04</rate> <sef>1.000</sef> </point> … </rate_table> </reaction> ….</reaction_data>
![Page 27: Nuclear Data Needs for r- Process Calculations Bradley Meyer Clemson University](https://reader030.vdocuments.mx/reader030/viewer/2022033103/56649e535503460f94b4926f/html5/thumbnails/27.jpg)
XML Data for Reactions—a single rate
<!-- o19 to f19 + electron + anti-neutrino_e -->
<reaction> <source>Nuclear Data tables</source> <reactant>o19</reactant> <product>f19</product> <product>electron</product> <product>anti-neutrino_e</product> <single_rate>1.6251e-01</single_rate></reaction>
![Page 28: Nuclear Data Needs for r- Process Calculations Bradley Meyer Clemson University](https://reader030.vdocuments.mx/reader030/viewer/2022033103/56649e535503460f94b4926f/html5/thumbnails/28.jpg)
XML Data for Reactions—a non-smoker fit
<!– ne15 + n to ne16 + gamma -><reaction> <source>ADNDT (2001) 75, 1 (non-smoker)</source> <reactant>ne15</reactant> <reactant>n</reactant> <product>ne16</product> <product>gamma</product> <non_smoker_fit> <Zt> 10</Zt> <At> 15</At> <Zf> 10</Zf> <Af> 16</Af> <Q> 8.071000</Q> <spint> 0.0000</spint> <spinf> 0.0000</spinf> <TlowHf>-1.0000</TlowHf> <Tlowfit> 0.0100</Tlowfit> <acc> 1.900000e-06</acc> <a1> 6.225343e+00</a1> <a2> 1.023384e-02</a2> <a3>-1.272184e+00</a3> <a4> 3.920127e+00</a4> <a5>-1.966720e-01</a5> <a6> 1.394263e-02</a6> <a7>-1.389816e+00</a7> <a8> 2.983430e+01</a8> </non_smoker_fit></reaction>
![Page 29: Nuclear Data Needs for r- Process Calculations Bradley Meyer Clemson University](https://reader030.vdocuments.mx/reader030/viewer/2022033103/56649e535503460f94b4926f/html5/thumbnails/29.jpg)
Zone data<initial_mass_fractions>
<multiple_zones>
<zone label1="x1" label2="y1" label3="z1"> <nuclide> <z>0</z> <a>1</a> <x>0.5</x> </nuclide> <nuclide> <z>1</z> <a>1</a> <x>0.5</x> </nuclide> </zone> … </multiple_zones></initial_mass_fractions>
![Page 30: Nuclear Data Needs for r- Process Calculations Bradley Meyer Clemson University](https://reader030.vdocuments.mx/reader030/viewer/2022033103/56649e535503460f94b4926f/html5/thumbnails/30.jpg)
Where we’re headed
• Release of libnucnet 0.3 imminent
• Put network code based on libnucnet on line this fall
• My research with libnucnet– Study nuclear network equilibria (NSE, QSE,
etc.)– Build a multi-zone Galactic chemical evolution
network on top of libnucnet.
![Page 31: Nuclear Data Needs for r- Process Calculations Bradley Meyer Clemson University](https://reader030.vdocuments.mx/reader030/viewer/2022033103/56649e535503460f94b4926f/html5/thumbnails/31.jpg)
Four Requirements for Meaningful Measurements for Astrophysics (The et al. 1998)
• An appropriate astrophysical model of events significant for nucleosynthesis . (“Appropriate” does not necessarily = “correct”!)
• An observable from the nucleosynthesis process, usually an abundance result that is either known or measurable.
• The dependency of the value of the observable on the value of a nuclear cross section or other nuclear property.
• An experimental strategy for measuring that cross section, or at least of using measurable data to better calculate it.