# Estimation of $M1$ scissors mode strength for deformed nuclei in the medium- to heavy-mass region by statistical Hauser-Feshbach model calculations

## Abstract

Radiative neutron capture is an important nuclear reaction whose accurate description is needed for many applications ranging from nuclear technology to nuclear astrophysics. The description of such a process relies on the Hauser-Feshbach theory which requires the nuclear optical potential, level density, and γ-strength function as model inputs. It has recently been suggested that the ** M1** scissors mode may explain discrepancies between theoretical calculations and evaluated data. We explore statistical model calculations with the strength of the

**scissors mode estimated to be dependent on the nuclear deformation of the compound system. We show that the form of the**

*M*1**scissors mode improves the theoretical description of evaluated data and the match to experiment in both the fission product and actinide regions. Since the scissors mode occurs in the range of a few keV to a few MeV, it may also impact the neutron capture cross sections of neutron-rich nuclei that participate in the rapid neutron capture process of nucleosynthesis. As a result, we comment on the possible impact to nucleosynthesis by evaluating neutron capture rates for neutron-rich nuclei with the**

*M*1**scissors mode active.**

*M*1- Authors:

- Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
- Charles Univ., Prague (Czech Republic)
- Univ. of Notre Dame, Notre Dame, IN (United States)

- Publication Date:

- Research Org.:
- Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

- Sponsoring Org.:
- USDOE National Nuclear Security Administration (NNSA)

- OSTI Identifier:
- 1419754

- Alternate Identifier(s):
- OSTI ID: 1375514

- Report Number(s):
- LA-UR-17-23922

Journal ID: ISSN 2469-9985; PRVCAN; TRN: US1801387

- Grant/Contract Number:
- AC52-06NA25396; SC0013039

- Resource Type:
- Accepted Manuscript

- Journal Name:
- Physical Review C

- Additional Journal Information:
- Journal Volume: 96; Journal Issue: 2; Journal ID: ISSN 2469-9985

- Publisher:
- American Physical Society (APS)

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 73 NUCLEAR PHYSICS AND RADIATION PHYSICS; Atomic and Nuclear Physics; scissors mode; neutron capture

### Citation Formats

```
Mumpower, Matthew Ryan, Kawano, Toshihiko, Ullmann, John Leonard, Krticka, Milan, and Sprouse, Trevor M. Estimation of M1 scissors mode strength for deformed nuclei in the medium- to heavy-mass region by statistical Hauser-Feshbach model calculations. United States: N. p., 2017.
Web. doi:10.1103/PhysRevC.96.024612.
```

```
Mumpower, Matthew Ryan, Kawano, Toshihiko, Ullmann, John Leonard, Krticka, Milan, & Sprouse, Trevor M. Estimation of M1 scissors mode strength for deformed nuclei in the medium- to heavy-mass region by statistical Hauser-Feshbach model calculations. United States. doi:10.1103/PhysRevC.96.024612.
```

```
Mumpower, Matthew Ryan, Kawano, Toshihiko, Ullmann, John Leonard, Krticka, Milan, and Sprouse, Trevor M. Thu .
"Estimation of M1 scissors mode strength for deformed nuclei in the medium- to heavy-mass region by statistical Hauser-Feshbach model calculations". United States. doi:10.1103/PhysRevC.96.024612. https://www.osti.gov/servlets/purl/1419754.
```

```
@article{osti_1419754,
```

title = {Estimation of M1 scissors mode strength for deformed nuclei in the medium- to heavy-mass region by statistical Hauser-Feshbach model calculations},

author = {Mumpower, Matthew Ryan and Kawano, Toshihiko and Ullmann, John Leonard and Krticka, Milan and Sprouse, Trevor M.},

abstractNote = {Radiative neutron capture is an important nuclear reaction whose accurate description is needed for many applications ranging from nuclear technology to nuclear astrophysics. The description of such a process relies on the Hauser-Feshbach theory which requires the nuclear optical potential, level density, and γ-strength function as model inputs. It has recently been suggested that the M1 scissors mode may explain discrepancies between theoretical calculations and evaluated data. We explore statistical model calculations with the strength of the M1 scissors mode estimated to be dependent on the nuclear deformation of the compound system. We show that the form of the M1 scissors mode improves the theoretical description of evaluated data and the match to experiment in both the fission product and actinide regions. Since the scissors mode occurs in the range of a few keV to a few MeV, it may also impact the neutron capture cross sections of neutron-rich nuclei that participate in the rapid neutron capture process of nucleosynthesis. As a result, we comment on the possible impact to nucleosynthesis by evaluating neutron capture rates for neutron-rich nuclei with the M1 scissors mode active.},

doi = {10.1103/PhysRevC.96.024612},

journal = {Physical Review C},

number = 2,

volume = 96,

place = {United States},

year = {2017},

month = {8}

}

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