For his original study on “Neutrino Flux Prediction for the NuMI Beamline,” Fermilab scientist Leo Aliaga Soplin, who works on the MINERvA experiment, received the 2017 URA Thesis Award on June 8 at the annual laboratory Users Meeting. Each year the Universities Research Association awards the most outstanding thesis conducted at Fermilab or in collaboration with Fermilab scientists.
The thesis introduced an improved method of predicting the behavior of subatomic particles known as neutrinos. Aliaga Soplin wrote his thesis as a graduate student at William & Mary working under the supervision of Michael Kordosky, associate professor in the Department of Physics. He received his Ph.D. in 2016.
“The committee was impressed both by the thoroughness and the originality of the neutrino flux study as well as its broad applicability to Fermilab’s neutrino program,” said Fermilab scientist Leonard Spiegel, chair of the award committee.
Neutrinos are elusive particles that could have played a major role in the evolution of the universe. Scientists work to unravel their mysteries by studying neutrinos generated by particle accelerators.
“Aliaga’s work is another step to help unravel those mysteries. His dedicated study of the neutrino creation process in accelerator-driven neutrino experiments will be an essential tool to further improve our understanding of these particles,” said Marta Cehelsky, executive director of the Universities Research Association.
Neutrinos can’t be produced directly – they are created by smashing protons into solid pieces of matter, called targets, to generate an avalanche of debris particles. Some of these particles then decay into neutrinos. To fully understand how many neutrinos are created in this way, Aliaga has studied those collisions of protons and any particle created in a Fermilab beamline, called the NuMI beamline, with matter and their debris in his thesis work.
“Knowing the neutrino flux – the number of neutrinos that is created – is essential for our experiment because we need it to understand our measurements," said Aliaga Soplin. “At MINERvA, we try to figure out how neutrinos interact with different kinds of matter, and to do this we use predictions for the neutrino flux. In my thesis, I have improved these predictions.”
Aliaga Soplin’s neutrino flux predictions start with the protons smashing into atoms to create other particles. This process is called hadron production. Those interactions between protons and atoms can be very diverse and depend strongly on conditions such as the kind of atom, the energy of the proton and the thickness of the target material.
Aliaga Soplin collected results and measurements of specific hadron production experiments that precisely measure what kind of debris are created and how they behave. Using this precise knowledge of hadron production at the NuMI beamline, he created a software tool to calculate the neutrino flux for the NuMI neutrino beam called Package to Predict the FluX, or PPFX.
“Receiving this award for my work here at Fermilab is a special honor for me, because it was a visit to Fermilab that inspired me to work on experiments in the first place,” Aliaga Soplin said. “I also feel deeply honored by the trust my colleagues put into my work by using it for their neutrino experiments.”
Aliaga Soplin’s software can be adapted for different experiments and is already used by the NOvA experiment and will be a baseline for the future accelerator-driven, international Deep Underground Neutrino Experiment.