About Me

I come from a family of 5 with 2 older siblings. One sister, Naomi, and one brother, Josiah. Naomi and Josiah are both out of college and are working for World Magazine and Honda respectively. My parents are living over seas again after they droped me off in college in Sri Lanka.

My passions include but are not limited to travel, hiking, driving, camping, and volleyball. Some of my favorite memories are doing hiking trips in the UP of Michigan and the Catalina Mountains in Arizona. I played volleyball and soccer in highschool and have always only been interested in those sports. I got my first motorcycle when I was 15 and have been riding all the time since then. My favorite activity is to do mountian biking in the mountians of Chang Mai.

I am studing physics becuase I want to try and be a part, however small, of the greats (Tesla, Einsitine, and So many others). I have beeing doing research for the physics deparetment of hope durring my time here. Due to that experiance I am condidering going into nuclear or particle physics or possibly quantum computing. Bellow I have described a bit more information on my research.

Research

For the past 3 years I have been working with Paul DeYoung at Hope and the SuN group at MSU doing research in astrophysics on Cobalt 52 and 53 and Nickel 53 and 55. Before getting into what I did specifically for this research it is first important to understand what astrophysics is.

Astrophysics is concerned with understanding the nature of stars and other celestial bodies such as the birth life and death of starts planets and galaxies. Another central question to astrophysics is how elements are created in the extreme environments such as our sun, star-mergers, and supernovae. There is a good understanding of fusion reactions which due is when two lighter elements merge together. However due a property known as the nuclear binding energy fusion only works until iron. There is not as good of an understanding of how elements heavier than iron are made. This is the branch of astrophysics where my work comes into play. There are 3 main processes that can be used for the production of elements heavier than iron: r-process, s-process and p-process. The first 2 (r and s process) are responsible for the production of neutron rich elements and the last (p-process) is responsible for the creation of proton rich elements (p-nuclei).

My work is to analyze 52,54 Co and 53,55 Ni, which are isotopes involved in p-process and are important in understanding the nucleosynthesis of proton-rich heavy elements. The analysis aims to extract characteristics such as the half life and something called the β-decay Intensity Function that is helpful to theorists. These isotopes are important for understanding p-nuclei because their half lives are not too long that experimentally measuring them is inconvenient or to short that it is impossible to measure. The end goal for obtaining these components for these isotopes is to provide experimental data for theorists so current nuclear models structure and calculations for the p process can be compared, checked, and improved to better match the fundamental intricacies of p process calculations.

To understand the work, I did there are two main decays important within the p-process for this experiment. The first is B+ decay which is where a proton is converted to a neutron. This decay yields a positron and a neutron. This decay it turns to a different element with an atomic number one less than before or to the left in the periodic table. So, for example in this experiment a cobalt isotope will beta plus decay into iron. The new element that it decays into is normally in a high energy state of the child nucleus.

After the beta plus decay the high energy child will then gamma decay down to the lowest energy state of that element. This gamma decay, which I just mentioned is the second decay important in p-process. It drops the energy down from a high level and yields just a gamma ray. Putting this all together the isotopes of interest beta plus decay which release a positron and electron that can be measured, then gamma decay from the high energy of the child down to the ground state releasing gamma rays along the way which can also be measured.

All data for this experiment was collected at the National Superconducting Cyclotron Laboratory (NSCL) with the Summing NaI(Tl) (SuN) detector and a Double-Sided Silicon Strip Detector (DSSD). The DSSD records the positrons from the beta plus decay as well as time information and the SuN detector records the individual gamma rays of the decays. This experiment uses Total absorption spectroscopy (TAS) to find the beta decay intensity function and Gammaw Teller transition function. TAS sums all γ rays released in the decay to find the energy levels in the child fed during decay. Two sets of data were taken one for Co52 and NI53 and another set of data for Co54 and Ni55.

In addition to finding the beta decay strength function and the Gammaw-teller Transition funciton, the half-lives of the isotopes can also inform nuclear models. Due to the DSSD detector having very precise time information, half-lives could also be extracted. The graphs to the right are decay curves recorded by ploting the time between the implant and the decay. By performing an exponential fit, decay constants can be determined and the half-lives calcualted. The accepted half-lives of these isotopes in the national nuclear database center (NNDC) are 104(7) ms and 193(7) ms for 52Co and 54Co respectively. The results from this experiment were 100(1.5) ms and 190(2.4) ms which fall in alignment with NNDC but are also more accurate.

The Beta intensity and gammaw teller transition functions can be extracted from information on what exited energy level the parent isotope decays into in the child. This information is found by performing a multidimensional χ2 minimization fit. To do the fit basis states for each decay path were created using GEANT4 which is a simulation program. These simulated spectra are fit to the experimental spectra and the fit coefficients are adjusted into percentages then put into another program which perfroms calculation to get both functions. GEANT makes the spectra by inputting the Q value of the isotope of interest, atomic number, experimental set up, and the decay paths from the NNDC.

Previous work performed Chi^2 minimization fits for only gamma decay spectra however an issue faced in this experiment is the appearance of another type of decay known as beta delayed proton emition. This type of decay is when a parent nuclus decays to a child then immediately emits a proton and decays to an even lower element on the periodic table. This type of decay has not been studied before using total absorption spectroscopy and so to obtain correct results for the Beta intensity Function strengths of the proton emission path must be found so that the beta decay paths can be adjusted and normalized accordingly. To find the proton emission path strength a similar process of fitting must be used on the beta decay spectra. However, because fitting for the DSSD has not been done before improvements had to be made to the DSSD spectra created by GEANT so that it matched experimental results. This was done by adding a randomization in the simulation that mimics the randomization in implantation position as well as changing where the thresholds are for the simulated data which mimics the limitations of the DSSD detector. Ni55 has no proton emission present, so it was used as the guinea pig and code was improved until the simulated data matched the experimental data which can be seen in the last slide.

The analysis is ongoing and final determinations for the Beta intensity and Gammaw teller transition functions are still yet to be found. In order to complete this project, the fitting including DSSD must be finalized and then preformed. Then of the information regarding this experiment must be put into a paper and published so that theorist can use this information to improve models and understanding of p-process.