Author: Andrew Puckett

SBS GEP experiment (E12-07-109) re-approved by JLab PAC47

Experiment E12-07-109, a measurement of the proton electromagnetic form factor ratio to Q2=12 GeV2 using the polarization transfer method, of which Professor Puckett is a spokesperson, was recently re-evaluated by the Jefferson Lab Program Advisory Committee at its 47th meeting in July (PAC47), under JLab’s jeopardy review process. Experiments that have been previously approved but are not yet scheduled after a certain time period must be periodically reviewed by the PAC to determine whether they are still relevant, and re-evaluated in terms of both beam time allocations and scientific rating and priority.

The PAC re-approved E12-07-109 with no changes in beam time allocation (45 PAC days) or scientific rating (“A-“). E12-07-109 is projected to run in 2022 based on current informal internal Hall A schedule planning.

The proposal update document submitted for the jeopardy review can be found here.

The figure below shows the projected accuracy of the proton form factor ratio measurements from E12-07-109, compared to existing world data and a selection of theoretical models:

Projected accuracy of E12-07-109 compared to existing data and selected theoretical models
Projected statistical precision of the upcoming proton form factor ratio measurements from E12-07-109, compared to existing data and selected theoretical models.


Professor Puckett Elected Chair of SBS Coordinating Committee

Starting August 5, 2019, Professor Puckett was elected by the current membership of the Super BigBite Spectrometer Collaboration Coordinating Committee (CC) to serve a one-year term as the chair of the committee.

The CC is the governing body of the SBS collaboration, formed to ensure the efficient preparation and execution of the experimental program, by identifying tasks which need to be carried out and identifying volunteers from the collaboration to carry out those tasks which the CC chooses to delegate, and by ensuring adequate communication between groups working on different aspects of the project, organizing informal weekly phone meetings and formal collaboration meetings twice a year.

Professor Puckett and group at Jefferson Lab, August 2019

UConn Group with BigBite detector package
From left to right: Sebastian Seeds, Provakar Datta, and Andrew Puckett with the BigBite detector package.

Professor Puckett and the graduate student and postdoc members of the group are at Jefferson Lab for the currently running “PREX-II” experiment in Hall A, ongoing detector assembly and cosmic ray commissioning work for the upcoming Super BigBite installation in Hall A, and for the SBS Collaboration Meeting on August 5-6. The PREX-II experiment is a precise measurement of the parity-violating asymmetry in low-Q2 elastic electron scattering from the 208Pb (Lead) nucleus. This measurement is highly sensitive to the “neutron skin thickness” of the lead nucleus, and constitutes a precise test of state-of-the-art nuclear theory and also has significant implications for the equation of state of neutron matter, relevant to the structure of neutron stars.

UConn graduate students Sebastian Seeds and Provakar Datta have been at JLab this summer assembling and cabling the detector package for the BigBite spectrometer, the main electron detector for the upcoming SBS family of experiments in Hall A, in preparation for cosmic ray testing and commissioning prior to installation in Hall A, currently scheduled for spring 2020.

Graduate Student Group Members attend HUGS 2019 at Jefferson Lab

Second-year graduate student group members Sebastian Seeds and Provakar Datta are participating in the 2019 Hampton University Graduate Studies (HUGS) summer school at Jefferson Lab.

Organized annually since 1986, The Hampton University Graduate Studies (HUGS) Summer Program at Jefferson Lab is an internationally renowned summer school in Nuclear Physics designed to train the nuclear workforce’s next generation of researchers. More details of the 2019 program can be found here.

Prof. Puckett gives colloquium at University of Tennessee

On Monday, March 11, 2019, Prof. Puckett delivered a colloquium at the University of Tennessee in Knoxville, TN. The title of the talk was “Nucleon imaging at the femtoscale via elastic electron-nucleon scattering.” The main subject of the talk was the upcoming high-momentum-transfer nucleon form factor measurements using SBS in Hall A at Jefferson Lab.

The slides from the talk can be viewed here.

Dr. Freddy Obrecht Defends Thesis (Successfully)

Congratulations to Dr. Richard F. (Freddy) Obrecht, who successfully defended his thesis, “Electric Form Factor of the Neutron From Asymmetry Measurements” on Friday, January 4, 2019.

Freddy analyzed the remaining unpublished measurement of the neutron electric form factor from experiment E02-013, that ran in Hall A in 2006, bringing it to a state of readiness for publication. He also independently re-analyzed the previously published results from the same experiment, and drafted the forthcoming archival publication for the whole experiment.

He is starting an Insight Data Science fellowship in NYC later this month, an intensive postdoctoral professional development fellowship designed to bridge the gap between academia and industry in data science. He will be missed by nuclear physics, but I know he will succeed in whatever he decides to do!

New article in Nuclear Instruments and Methods Section A

The GEp-III/GEp-2γ collaboration, with Professor Puckett as the lead author, drafted a paper describing technical aspects of the data analysis of both experiments, including the details of the final systematic uncertainty evaluation. The paper, published in Nuclear Instruments and Methods Section A, volume 910, pages 54-78 (2018),  was intended as a supplement to our recent archival publication, and as a reference for use by future experiments and/or data analyses using the same or similar equipment and methods.