Nuclear Physics Seminars This Term

The REDTOP experiment is a super-η/η′ factory aiming at exploring physics BSM, and Cold Dark Matter in particular, in the MeV-GeV energy range. This range is, at present, the most unconstrained among the energy regions searched by current and planned experiments. The η and η′ mesons are almost unique in the particle universe. Their quantum numbers are all zero, which occurs only for the Higgs boson and the vacuum (except for parity). In that respect, REDTOP is considered a low-energy Higgs factory. Furthermore, less than 80REDTOP aims at collecting more than 10¹⁴ η/yr (10¹² η’/yr) in a 3-year running period, corresponding to about five order of magnitude of the current world sample. Such statistics is sufficient for investigating several symmetry violations, and for searching particles and forces beyond the Standard Model, including dark matter, by studying rare decays of the η and η′. Recent physics and detector studies indicate that REDTOP has excellent sensitivity to probe all four portals connecting the dark sector with the Standard Model, a feature reached only by the SHIP experiment at CERN. Furthermore, conservation laws and violation of discrete symmetries can be probed in several ways. REDTOP is the only η/η′ factory being proposed in the world. The advanced design of the detector is the key of the experiment. A modest proton beam with low power (30 W) is required. Recent physics and detector studies indicate that REDTOP has excellent sensitivity to probe all four portals connecting the dark sector with the Standard Model. Furthermore, conservation laws and violation of discrete symmetries can be probed in several ways. The physics program and the detector for REDTOP will be discussed during the presentation.

The Electron-Ion Collider (EIC) is the next-generation US-based project for QCD and nuclear science. It will collide polarized electrons with polarized protons and light ions, as well as heavier ions across the full mass range, at a high luminosity, over a wide range of c.m. energies. The first detector (ePIC) will support a broad science program, but having two detectors would significantly expand the capabilities of the EIC. The possibility to cross check results between the two detectors will enhance the discovery potential, and as in the case of H1 and ZEUS, combining data could reduce the overall systematic uncertainties. The latter will be even more relevant for the EIC than it was for HERA since once the luminosity ramps up to its nominal value, most EIC measurements will be limited by systematics. And those that require the highest luminosities (e.g., exclusive reactions and femtography of nucleons and nuclei) would greatly benefit from an improved far-forward near-beam acceptance, which is the main feature of the interaction region (IR8) where the 2nd detector could be located. The ability to detect recoiling light nucleus in coherent processes down to pT = 0, as well as almost all nuclear fragments in reactions where the nucleus breaks up (which also can be used to veto breakup in medium and heavy nuclei) will enhance the nuclear part of the EIC program and making it the ideal tool for femtography in the region dominated by sea quarks and gluons. The 2nd detector will also provide complementary capabilities to ePIC in other areas (e.g., improved muon detection), and will benefit from the ongoing Generic EIC Detector R&D program. This seminar will give an introduction to the 2^nd detector, with a particular focus on exclusive reactions, and discuss some of the unique opportunities that a 2nd detector could bring to the EIC.

The JLab Super Bigbite Spectrometer (SBS) program’s primary goal is to determine the elastic nucleon form factors at high momentum transfer. The SBS program includes a measurement of the neutron electric form factor, GEn, using the double-polarization technique with both a polarized electron beam and a polarized He-3 target. In order to obtain adequate statistics in the high Q2 region, the polarized He-3 target has operated with a polarization-weighted luminosity approximately a factor of three above any previous polarized He-3 target used in an electron-scattering experiment. The analysis of this experiment aims to extract GEn at Q2 values of 3.0 , 6.8, and 9.8 GeV2. This talk will include a brief introduction to form factors, specifically, GEn, a description of the major hardware subsystems crucial to running the experiment, progress on the target analysis, and finally a brief look into the early stages of data analysis.

In some theories beyond the Standard Model, new force mediating bosons appear as explanations for dark matter. If such forces exist, they are necessarily weak to be so far undetected. It is then desirable to search for these particles with neutrons, which have the benefit of electric neutrality and small polarizability, significantly reducing experimental false effects from stray electric fields. In this talk, I will discuss how one can utilize the localization of neutrons along a curved surface, a phenomenon called the "neutron whispering gallery effect," to search for these new forces; and the measurements of this effect made at the Institut Laue Langevin will be described.

The whispering gallery effect is also predicted to exist with anti-atoms, and an experiment with this effect could support recent campaigns to measure the gravitational acceleration of anti-matter. The methodology of such an experiment will be explained and preliminary results of a recent proof of principle experiment with the neutron whispering gallery will be shared.

TBA