Statistical Nuclear Physics and (α,n) Reactions for ... · Statistical Nuclear Physics and (α, n)...

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Statistical Nuclear Physics and (α,n) Reactions for Applications Zach Meisel (Ohio University), DE-NA0003909 Goal : To increase the accuracy and predictive power of statistical descriptions of nuclear reactions. This is done by benchmarking model calculations against experimental data. Specifically, nuclear level-densities are measured via particle evaporation spectra and (α,n) cross sections are directly measured. Personnel : The experimental low-energy nuclear physics group at Ohio University (bold green are funded by this work) Faculty: Zach Meisel, Alexander Voinov, Carl Brune, Steve Grimes, Tom Massey Postdoctoral Research Associates: Mansi Saxena Graduate Students: Kristyn Brandenburg, Michael Hartos, Joseph Derkin, Gula Hamad,Yenuel Jones-Alberty, Som Paneru, Doug Soltesz, Shiv Subedi, Justin Warren Products : 9 publications and 7 invited presentations Published Outcome: A.V. Voinov et al. PRC 99, 054609 (2019)

Transcript of Statistical Nuclear Physics and (α,n) Reactions for ... · Statistical Nuclear Physics and (α, n)...

Page 1: Statistical Nuclear Physics and (α,n) Reactions for ... · Statistical Nuclear Physics and (α, n) Reactions for Applications Zach Meisel (Ohio University), DE-NA0003909 Goal: To

Statistical Nuclear Physics and (α,n) Reactions For Applications (Zach Meisel, Ohio University) 1

Statistical Nuclear Physics and (α,n) Reactions for ApplicationsZach Meisel (Ohio University), DE-NA0003909

Goal: To increase the accuracy and predictive power of statistical descriptions of nuclear reactions. This is done by benchmarking model calculations against experimental data. Specifically, nuclear level-densities are measured via particle evaporation spectra and (α,n) cross sections are directly measured.

Personnel: The experimental low-energy nuclear physics group at Ohio University(bold green are funded by this work)

• Faculty: Zach Meisel, Alexander Voinov, Carl Brune, Steve Grimes, Tom Massey• Postdoctoral Research Associates: Mansi Saxena• Graduate Students: Kristyn Brandenburg, Michael Hartos, Joseph Derkin,

Gula Hamad, Yenuel Jones-Alberty, Som Paneru, Doug Soltesz,Shiv Subedi, Justin Warren

Products: 9 publications and 7 invited presentationsPublished Outcome: A.V. Voinov et al. PRC 99, 054609 (2019)

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Statistical Nuclear Physics and (α,n) Reactions For Applications (Zach Meisel, Ohio University) 2

X-ray burstsNeutrino-driven winds (proton-rich)Core collapse supernovae shocksNeutrino-driven winds (neutron-rich)Neutron star mergersNeutron star crusts

Nuclear properties are needed across the nuclear landscape

Applications with Fissile Materials Extreme Astrophysical Environments

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Hauser-Feshbach formalism: The approach to calculate σstatisticalSy

stem

Ene

rgy ECM

X + a

Z

γ Y + b

ba

Reaction of Interest

Z

β+ decay or

Reaction

Easier to Perform Reaction

ba

γ

Formation Decay

Formation

Decay

𝜎𝜎𝑋𝑋 𝑎𝑎,𝑏𝑏 𝑌𝑌𝐻𝐻𝐻𝐻 = 𝜋𝜋

λ𝜋𝜋

2

�𝐽𝐽

2𝐽𝐽 + 1(2𝐽𝐽𝑎𝑎 + 1)(2𝐽𝐽𝑋𝑋 + 1)

𝑊𝑊𝑎𝑎𝑏𝑏𝑇𝑇𝑎𝑎𝑋𝑋𝑇𝑇𝑏𝑏𝑌𝑌

∑𝑐𝑐ℎ𝑎𝑎𝑎𝑎 𝑇𝑇𝑐𝑐ℎ𝑎𝑎𝑎𝑎

Formation

Decay

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The Edwards Accelerator Laboratory at Ohio University

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HF ingredients: Level densities, strength functions, & optical potentials

𝜎𝜎𝑋𝑋 𝑎𝑎,𝑏𝑏 𝑌𝑌𝐻𝐻𝐻𝐻 = 𝜋𝜋

λ𝜋𝜋

2

�𝐽𝐽

2𝐽𝐽 + 1(2𝐽𝐽𝑎𝑎 + 1)(2𝐽𝐽𝑋𝑋 + 1)

𝑊𝑊𝑎𝑎𝑏𝑏𝑇𝑇𝑎𝑎𝑋𝑋𝑇𝑇𝑏𝑏𝑌𝑌

∑𝑐𝑐ℎ𝑎𝑎𝑎𝑎 𝑇𝑇𝑐𝑐ℎ𝑎𝑎𝑎𝑎is a bit too cute for it’s own good…

Get from γ-strength function(or, for particles, optical model potential)

Level Densityof decay daughter

For one calculation, need several OMPs, γSFs, and ρLD:For each channel:

Reasonable input choices can lead to order-of-magnitude+ reaction rate uncertainties.

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Nuclear Level Density is hard to predict on stability, and is poorly constrained off

CS impact of LD on (n,γ) on stable isotopesBeard et al. PRC 2014

Spread in LD predictions & data for…

52Cr

60Zn

Zelevinsky & HoroiPPNP 2019

Soltesz et al. In PrepAl Quraishi et al.

PRC 2001

LD reduction off-stability has been suggested empirically and based on considering “effective level density”

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Our approach to constraining nuclear level density:The particle evaporation method

Y + b

b

Number of decays to daughter states (Y) will be related to the number of states within an excitation

energy region

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Our approach to constraining nuclear level density:The particle evaporation method

A.V. Voinov et al. PRC 2019

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Our goal is to establish systematics of the nuclear level density

A.V. Voinov et al. PRC 2019

Year 1 results:• 74,76Ge level densities are lower than many predictions

(excellent agreement with SM: Ormand & Brown arXiv:1912.08973)

and D0• This impacts LD extractions requiring

normalization at high energies• 59Mn decay analysis ongoing (BSFG favored for 58Cr)

Michael Hartos (GS)

74Ge

76Ge

24Mg(7Li,p)In collaboration with

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(α,n) reactions matter for many applications, yet direct data are sparse

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86Se(α,xn) P. Mohr PRC 2016

The (α,n) cross section dependency on the αOMP means that measurements can improve theoretical estimates for nuclides

in a similar region of the nuclear chart

J. Glorius et al. PRC 2014

R. Talwar et al. PRC 2018

(α,n) theory predictions depend on the α optical potential (αOMP)

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HeBGB, custom built for (α,n) measurements at the EALK. Brandenburg MS Thesis (OU) 2017

Kristyn Brandenburg (GS)

27Al(α,n)

online analysis

Year 1 results:• Completed with SSAA funds• Validated efficiency with

51V(p,n) and 13C(α,n)• Performed first cross section

measurement: 27Al(α,n)• Analyses are ongoing

Gula Hamad (GS)

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Join us in Athens, OH this July!

Meeting emphasis:• limits of the statistical model• overlaps between statistical nuclear physics for astrophysics and applications• fission and the r-process

INPP.OHIO.EDU/~T3

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Thanks to: my collaborators and