Mateus Carneiro in the neutrino lab

Postdoc Mateus Carneiro has moved on to a position at Brookhaven National Laboratory but he left us with a really nice paper in Physics Review Letters.

M.Carneiro et al. [MINERvA], “High-Statistics Measurement of Neutrino Quasielasticlike Scattering at 6 GeV on a Hydrocarbon Target”, Phys. Rev. Lett. 124, no.12, 121801 (2020), doi:10.1103/PhysRevLett.124.121801

Graduate Student Amit Bashyal did many of the cross-checks for this complicated measurement and wrote a summary for FermiNews which is copied below. Amit’s thesis topic is the parallel measurement for anti-neutrinos.

Playing pool with neutrinos

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Hard to believe you can play pool with neutrinos, but certain neutrino interaction events are closer to the game than you think.

In these charged-current quasielastic interactions — let’s call them CCQE interactions for short — a neutrino strikes a particle in an atom’s nucleus — a proton or a neutron. Two particles emerge from the collision. One is a muon, a heavier cousin of the electron. The other is either a proton (if the stationary particle is a neutron) or a neutron (if the stationary particle is a proton).

The neutrino interactions that result from these quasielastic reactions are like the collisions between balls in a game of pool: You can guess the energy of the incoming neutrino by measuring the direction and energy of only one of the outgoing particles, provided you know the types of all four particles that were in the interaction in the first place and the original direction of the neutrino.

CCQE interactions are an important interaction mode of neutrinos in current and future neutrino oscillation experiments, such as the international Deep Underground Neutrino Experiment, hosted by Fermilab.

They are similar to the elastic interactions every pool player knows except in one important way: The weak nuclear force allows the particles to change from one kind into another, hence the “quasielastic” name. In this subatomic pool game, the cue ball (neutrino) strikes a stationary red ball (proton), which emerges from the collision as an orange ball (neutron).

This display shows a CCQE-like event reconstructed in the MINERvA detector. Image: MINERvA

Since most modern neutrino experiments use targets made of heavy nuclei ranging from carbon to argon, nuclear effects and correlations between the neutrons and protons inside the nucleus can cause significant changes in the observed interaction rates and modifications to the estimated neutrino energy.

At MINERvA, scientists identify the CCQE interactions by a long muon track left in the particle detector and potentially one or more proton tracks. However, this experimental signature can sometimes be produced by non-CCQE interactions due to nuclear effects inside the target nucleus. Similarly, nuclear effects can also modify the final-state particles to make a CCQE event look like a non-CCQE event and vice versa.

Since nuclear effects can make it challenging to identify a true CCQE event, MINERvA reports measurements based on the properties of the final-state particles only and calls them CCQE-like events (since they will have contributions from both true CCQE and non-CCQE events). A CCQE-like event is one that has at least one outgoing muon, any number of protons or neutrons, and no mesons as final-state particles. (Mesons, like protons and neutrons, are made of quarks. Protons and neutrons have three quarks; mesons have two.)

MINERvA has measured the likelihood of CCQE-like neutrino interactions using Fermilab’s medium-energy neutrino beam, with the neutrino flux peaking at 6 GeV. Compared to MINERvA’s earlier measurements, which were conducted with a low-energy beam (3 GeV peak neutrino flux), this measurement has the advantage of a broader energy reach and much larger statistics: 1,318,540 CCQE-like events compared to 109,275 events in earlier low-energy runs.

MINERvA made these CCQE interaction probability measurements as a function of the square of the momentum transferred by the neutrino to the nucleus, which scientists denote as Q2. The plot shows discrepancies between the data and most predictions in low-Q2 and high-Q2 regions. By comparing MINERvA’s measurement with various models, scientists can refine them and better explain the physics inside the nuclear environment.

This plot shows the ratio of cross-section as a function of Q2 of data and various predictions with respectto one commonly used interaction model. Image: MINERvA

MINERvA has also made more detailed measurements of the probability of neutrino interaction based on the outgoing muon’s momentum. They take into account the muon’s momentum both in the direction of the incoming neutrino’s trajectory and in the direction perpendicular to its trajectory. This work helps current and future neutrino experiments understand their own data over a wide range of muon kinematics.

Mateus Carneiro, formerly of the Brazilian Center for Research in Physics and Oregon State University and now at Brookhaven National Laboratory, and Dan Ruterbories of the University of Rochester were the main drivers of this analysis. The results were published in Physical Review Letters.

Amit Bashyal is an Oregon State University scientist on the MINERvA experiment.

This work is supported by the DOE Office of Science, National Science Foundation, Coordination for the Improvement of Higher Education Personnel in Brazil, Brazilian National Council for Scientific and Technological Development, Mexican National Council of Science and Technology, Basal Project in Chile, Chilean National Commission for Scientific and Technological Research, Chilean National Fund for Scientific and Technological Development, Peruvian National Council for Science, Technology and Technological Innovation, Research Management Directorate at the Pontifical Catholic University of Peru, National University of Engineering in Peru, Polish National Science Center and UK Science and Technology Facilities Council.

Fermi National Accelerator Laboratory is supported by the Office of Science of the U.S. Department of Energy. The Office of Science is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time. For more information, visit science.energy.gov.

Mateus Carneiro in the neutrino lab
Mateus Carneiro in the neutrino lab

Welcome to Mateus Fernandes Carneiro who has joined the Schellman neutrino group as a postdoctoral scholar.  Mateus just completed his dissertation “Measurement of Muon Neutrino Quasi-Elastic Scattering on a Hydrocarbon Target at Enu of 6 GeV” at the Centro Brasileiro de Pesquisas Fisicas using the MINERvA neutrino detector at Fermilab.  He will be working with Heidi Schellman and Amit Bashyal on studies of neutrino cross sections.  Mateus will be working from Fermilab most of the time but will visit us frequently.

Leah Welty-Rieger got her PhD from the University of Indiana on the D0 experiment. After a year as a web designer she joined the Schellman group as a postdoc.  While at Northwestern she independently applied for and received a URA Fellowship to join the g-2 magnetic moment experiment.  She now works part-time as a GEANT consultant for the g-2 experiment at Fermilab.

Who says postdocs can't have kid (and Cub's tickets).
Who says postdocs can’t have kids (and Cubs tickets).
We just posted our new postdoctoral scholar position.  The location is most likely Fermilab but we’ll consider people interested in working in Corvallis.

 

MicroBooNE/MINERvA (AJO-5824)

Oregon State U. – Postdoc

Field of Interest: hep-ex, nucl-ex
Experiment: FNAL-E-0974, FNAL-E-0938
Deadline: 2015-10-01
Region: North America
Job description:
Oregon State University is seeking a postdoctoral scholar to participate in the MicroBooNE and MINERvA experiments at Fermilab. The Oregon State group’s expertise is in data handling, validation and algorithms and our physics interest is in precision measurements of neutrino cross section in the energy regimes relevant to future neutrino oscillation experiments. The position will most likely be at Fermilab in Illinois.

We are looking for someone with prior experimental experience in either high energy physics or nuclear physics, not restricted to neutrino physics. Significant expertise in modern scientific computing and data analysis is a plus.

For full consideration, please apply by 10/1/2015

Please apply via academicjobs online at https://academicjobsonline.org/ajo/jobs/5824
Contact: Heidi Schellman
Email: schellma@fnal.gov
More Information: https://academicjobsonline.org/ajo/jobs/5824

http://inspirehep.net/record/1386441