$U(r)=-\frac{W_0r_0}{r}\exp\left(-\frac{r}{r_0}\right)$
$\frac{E_{bind}}{c^2}=a_1A-a_2A^{2/3}-a_3\frac{Z(Z-1)}{A^{1/3}}-a_4\frac{(N-Z)^2}{A}+\epsilon a_5A^{-3/4}$
$R=R_0\left[1+\sum_{lm}a_{lm}Y_l^m(\theta,\varphi)\right]$

# Matthew Mumpower

Staff Scientist @ Los Alamos National Lab

I'm a theoretical physicist working at Los Alamos National Lab. I received my PhD at North Carolina State University under the direction of Gail McLaughlin. At the University of Notre Dame I worked under the direction of Ani Aprahamian and Rebecca Surman. My research interests are in nuclear structure and reaction mechanisms. The study of these models has a wide range of applicability from nuclear medicine, to stockpile stewardship and even the cosmos.

At Los Alamos we seek to solve national security challenges through scientific excellence. This means we not only apply our models to the task at hand, but we seek to push them to the limits by probing the edges of our knowledge with basic science research. One way I contribute to basic science research at the lab is to study the applicability of LANL nuclear models to nucleosynthesis. Nucleosynthesis is the study of the processes by which chemical elements are synthesized in cosmic environments. In other words, this part of my research focuses on how the elements on the periodic table were created. This field is extremely challenging and also very rewarding with many real world applications. Check out the research section of this website for more information.

I firmly believe that practicing in scientific inquiry is both empowering and a necessary requirement for success in today's world. You can learn more about my teaching efforts in the teach section of this website.

Outside of Physics I enjoy keeping up with latest technology trends and coming up with unique solutions to challenging problems. For more about my entrepreneurial endeavours check out Solace Development Group. In my free time I try to stay in shape by playing racquetball. If you are interested in a game, shoot me an e-mail.

## Latest Paper (October 17th 2017)

### The Origin of r-Process Elements in the Milky Way

Some of the heavy elements, such as gold and europium (Eu), are almost exclusively formed by the rapid neutron capture process (r-process). However, it is still unclear which astrophysical site between core-collapse supernovae and neutron star - neutron star (NS-NS) mergers produced most of the r-process elements in the universe. Galactic chemical evolution (GCE) models can test...

# Select Papers

#### Neutron-capture rates for explosive nucleosynthesis: the case of $^{68}$Ni$(n,\gamma)^{69}$Ni

A. Spyrou et al.
J. Phys. G 44 4 044002 - Published February 23rd 2017
Neutron-capture reactions play an important role in heavy element nucleosynthesis, since they are the driving force for the two processes that create the vast majority of the heavy elements. When a neutron capture occurs on a short-lived nucleus, it is extremely challenging to study the reaction directly and therefore the use of indirect techniques is essential. The present work reports on such an indirect measurement that provides strong constraints on the $^{68}$Ni(n,$\gamma$)$^{69}$Ni reaction rate. This is done by populating the compound nucleus $^{69}$Ni via the $\beta$ decay of $^{69}$Co and measuring the $\gamma$-ray deexcitation of excited states in $^{69}$Ni. The $\beta$-Oslo method was used to extract the $\gamma$-ray strength function and the nuclear level density. In addition the half-life of $^{69}$Co was extracted and found to be in agreement with previous literature values. Before the present results, the $^{68}$Ni(n,$\gamma$)$^{69}$Ni reaction was unconstrained and the purely theoretical reaction rate was highly uncertain. The new uncertainty on the reaction rate based on the present experiment (variation between upper and lower limit) is approximately a factor of 3. The commonly used reaction libraries...

#### The impact of uncertain nuclear masses near closed shells on the $r$-process abundance pattern

M. Mumpower, R. Surman, D.-L. Fang, M. Beard, A. Aprahamian
J. Phys. G 42 034027 - Published February 5th 2015
Calculations of rapid neutron capture nucleosynthesis involve thousands of pieces of nuclear data for which no experimental information is available. Of the nuclear data sets needed for $r$-process simulations---masses, $\beta$-decay rates, $\beta$-delayed neutron emission probabilities, neutron capture rates, fission probabilities and daughter product distributions, neutrino interaction rates---masses are arguably the most important, since they are a key ingredient in the calculations of all of the other theoretical quantities. Here we investigate how uncertainties in nuclear masses translate into uncertainties in the final abundance pattern produced in $r$-process simulations. We examine the influence of individual mass variations on three types of $r$-process simulations---a hot wind, cold wind, and neutron star merger $r$ process---with markedly different $r$-process paths and resulting final abundance patterns. We find the uncertainties in the abundance patterns due to the mass variations exceed the differences due to the astrophysics. This situation can be improved, however, by even modest reductions in mass...

## Racquetball

In my free time I play competitive racquetball. I was one of the top ranked players of the North Carolina State University Racquetball Club from 2008 to 2012. I designed their website which you can find an image of right here.