University of New Hampshire · Department of Physics & Astronomy
Nuclear & Particle Physics Group
We search for physics beyond the Standard Model and study how the structure and spin of nucleons and light nuclei arise from the strong interaction, leading experiments at Jefferson Lab and operating our own polarized target lab at UNH.
Welcome
Two of the big questions in physics
Welcome to the web pages of the UNH Nuclear and Particle Physics Group (NPG), part of the UNH Department of Physics & Astronomy. The group is located in the rebuilt DeMeritt Hall. Our research is aimed at two primary areas of study:
- Searches for physics beyond the Standard Model;
- Understanding the structure of the nucleon and light nuclei, and how this can be described in terms of the strong interaction and spin degrees of freedom.
These mission goals map to two of the top science questions for the 21st century: “What is Dark Matter?” and “What is the missing spin of the nucleon?”
We lead several multi-national collaborations at Jefferson Lab, and are preparing for several additional experiments at this facility. Jefferson Lab is now running at up to 12 GeV after a $314M upgrade, which was highlighted as the top priority of the last NSAC (Nuclear Science Advisory Committee) report.
There are four full-time faculty: Maurik Holtrop, Elena Long, Nathaly Santiesteban, and Karl Slifer. Over the past decade we have mentored nine PhDs and more than twenty undergraduates. These students make significant contributions to our efforts both at UNH and at Jefferson Lab, where they work side by side with some of the top scientists in the field.
Research
Our main experimental efforts
Tensor spin observables
UNH is at the forefront of a novel program to investigate tensor spin observables using a new solid tensor polarized target. The JLab b1 (spokespersons: Slifer, Long, Santiesteban) and Azz (spokespersons: Long, Santiesteban, Slifer) experiments were both fully approved in 2022, and their high physics ratings were affirmed by JLab PAC 51 in 2023. A main focus of our group is preparation for the Experimental Readiness Review and installation of the polarized target at Jefferson Lab.
Tensor polarization experiments →
Heavy Photon Search
HPS (spokesperson: Holtrop) searches for a new gauge boson—the heavy photon—as a potential particle in a hidden sector that could also contain the Dark Matter.
Heavy Photon Search →
Polarized Target Lab
A cryogenically cooled solid polarized target operating at 1 K and 5–7 T, using a mm-wave solid-state source to drive Dynamic Nuclear Polarization of deuterated samples.
Polarized Target Lab →Also from our group
- The g2p experiment (spokesperson: Slifer) investigates the spin structure of the proton and how this affects the energy levels of hydrogen-like systems. The data was recently published in Nature Physics.
- The Isospin SRC experiment (spokesperson: Solvignon) used a tritium target to probe how short-range correlations between nucleons affect the structure of nuclei.
Polarized target facilities
The NPG operates a cryogenically cooled solid polarized target lab in support of the Tensor Spin Observables program. We recently installed a new helium reliquefier system from Quantum Technologies to support the DNP system. We also operate a material preparation lab where we chemically introduce the paramagnetic impurities necessary for the DNP process, or alternately introduce these centers via irradiation at the NIST MIRF accelerator.