First application of the n − Be 9 optical potential to the study of the Be 10 continuum via the ( O 18 , O 17 ) neutron-transfer reaction

The $^{9}\mathrm{Be}(^{18}\mathrm{O},^{17}\mathrm{O})^{10}\mathrm{Be}$ reaction has been studied at an incident energy of 84 MeV, and the ejectiles have been detected at forward angles. The $^{10}\mathrm{Be}$ excitation energy spectrum has been obtained up to about 18 MeV, and several known bound and resonant states of $^{10}\mathrm{Be}$ have been identified. Calculations that describe the interaction of the neutron removed from the $^{18}\mathrm{O}$ projectile with the $^{9}\mathrm{Be}$ target by means of an optical potential with a semiclassical approximation for the relative motion account for a significant part of the $^{10}\mathrm{Be}$ continuum. Two parametrizations of the optical-model potential for the system n\text{\ensuremath{-}}^{9}\mathrm{Be} have been used and compared

The HPS electromagnetic calorimeter

The Heavy Photon Search experiment (HPS) is searching for a new gauge boson, the so-called “heavy photon.” Through its kinetic mixing with the Standard Model photon, this particle could decay into an electron-positron pair. It would then be detectable as a narrow peak in the invariant mass spectrum of such pairs, or, depending on its lifetime, by a decay downstream of the production target. The HPS experiment is installed in Hall-B of Jefferson Lab. This article presents the design and performance of one of the two detectors of the experiment, the electromagnetic calorimeter, during the runs performed in 2015–2016. The calorimeter's main purpose is to provide a fast trigger and reduce the copious background from electromagnetic processes through matching with a tracking detector. The detector is a homogeneous calorimeter, made of 442 lead-tungstate (PbWO4) scintillating crystals, each read out by an avalanche photodiode coupled to a custom trans-impedance amplifier

Dark matter search with the BDX-MINI experiment

BDX-MINI is a beam dump experiment optimized to search for Light Dark Matter produced in the interaction of the intense CEBAF 2.176 GeV electron beam with the Hall A beam dump at Jefferson Lab. The BDX-MINI detector consists of a PbWO$_4$ electromagnetic calorimeter surrounded by a hermetic veto system for background rejection. The experiment accumulated $2.56 \times 10^{21}$ EOT in six months of running. Simulations of fermionic and scalar Dark Matter interactions with electrons of the active volume of the BDX-MINI detector were used to estimate the expected signal. Data collected during the beam-off time allowed us to characterize the background dominated by cosmic rays. A blind data analysis based on a maximum-likelihood approach was used to optimize the experiment sensitivity. An upper limit on the production of light dark matter was set using the combined event samples collected during beam-on and beam-off configurations. In some kinematics, this pilot experiment is sensitive to the parameter space covered by some of the most sensitive experiments to date, which demonstrates the discovery potential of the next generation beam dump experiment planned at intense electron beam facilities.Comment: (13 pages, 11 figures

Exclusive ⁻ Electroproduction Off The Neutron In Deuterium In The Resonance Region

New results for the exclusive and quasifree cross sections off neutrons bound in deuterium vn(p) → pπ− (p) are presented over a wide final state hadron angle range with a kinematic coverage of the invariant mass (W) up to 1.825 GeV and the four-momentum transfer squared (Q2) from 0.4 to 1.0 GeV2. The exclusive structure functions were extracted and their Legendre moments were obtained. Final-state-interaction contributions have been kinematically separated from the extracted quasifree cross sections off bound neutrons solely based on the analysis of the experimental data. These new results will serve as long-awaited input for phenomenological analyses to extract the Q2 evolution of previously unavailable n → N∗ electroexcitation amplitudes and to improve state-of-the-art models of neutrino scattering off nuclei by augmenting the already available results from free protons

Vanadyl phthalocyanines on graphene/SiC(0001): toward a hybrid architecture for molecular spin qubits

Vanadyl phthalocyanine (VOPc) contains a highly coherent spin S = ½, which is of interest for applications in quantum information. Preservation of long coherence times upon deposition on conductive materials is crucial for use of single-spin in devices. Here, we report a detailed investigation of the structural, electronic and magnetic properties of a hybrid architecture constituted by a monolayer film of VOPc molecules deposited on graphene/SiC(0001). Graphene (Gr) is a two-dimensional conductor with exceptional chemical stability, a property which we exploited here to preserve the spin of VOPc. Low temperature-scanning tunneling microscopy supported by density functional theory (DFT) simulations revealed that VOPc molecules were adsorbed intact on the Gr/SiC(0001) surface in a planar geometry assuming a unique configuration in which the vanadyl group is projected out toward the vacuum, different to that found commonly on other conductive surfaces. Furthermore, X-ray photoelectron spectroscopy and UV-photoelectron spectroscopy (flanked theoretically by DFT) showed that VOPc interact weakly with the Gr/SiC(0001) substrate to preserve its electronic configuration with the unpaired electron located on the V ion. These findings were confirmed by X-ray magnetic circular dichroism, revealing that the S = ½ character of the VOPc assembly on Gr/SiC(0001) was preserved, in agreement with the theoretical prediction. Hence, molecules could be adsorbed and used as qubits on substrates of technological importance, such as graphene. This new hybrid architecture could be employed for local investigation of static and dynamic spin properties and as molecular qubits for spintronic applications

Minimalism in Radiation Synthesis of Biomedical Functional Nanogels

A scalable, single-step, synthetic approach for the manufacture of biocompatible, functionalized micro- and nanogels is presented. In particular, poly(N-vinyl pyrrolidone)-grafted-(aminopropyl)methacrylamide microgels and nanogels were generated through e-beam irradiation of PVP aqueous solutions in the presence of a primary amino-group-carrying monomer. Particles with different hydrodynamic diameters and surface charge densities were obtained at the variance of the irradiation conditions. Chemical structure was investigated by different spectroscopic techniques. Fluorescent variants were generated through fluorescein isothiocyanate attachment to the primary amino groups grafted to PVP, to both quantify the available functional groups for bioconjugation and follow nanogels localization in cell cultures. Finally, a model protein, bovine serum albumin, was conjugated to the nanogels to demonstrate the attachment of biologically relevant molecules for targeting purposes in drug delivery. The described approach provides a novel strategy to fabricate biohybrid nanogels with a very promising potential in nanomedicine

Artificial Intelligence for the Electron Ion Collider (AI4EIC)

The Electron-Ion Collider (EIC), a state-of-the-art facility for studying the strong force, is expected to begin commissioning its first experiments in 2028. This is an opportune time for artificial intelligence (AI) to be included from the start at this facility and in all phases that lead up to the experiments. The second annual workshop organized by the AI4EIC working group, which recently took place, centered on exploring all current and prospective application areas of AI for the EIC. This workshop is not only beneficial for the EIC, but also provides valuable insights for the newly established ePIC collaboration at EIC. This paper summarizes the different activities and R&D projects covered across the sessions of the workshop and provides an overview of the goals, approaches and strategies regarding AI/ML in the EIC community, as well as cutting-edge techniques currently studied in other experiments.Comment: 27 pages, 11 figures, AI4EIC workshop, tutorials and hackatho

Improved exclusion limit for light dark matter from e+e- annihilation in NA64

The current most stringent constraints for the existence of sub-GeV dark matter coupling to Standard Model via a massive vector boson A′ were set by the NA64 experiment for the mass region mA′≲250 MeV, by analyzing data from the interaction of 2.84×1011 100-GeV electrons with an active thick target and searching for missing-energy events. In this work, by including A′ production via secondary positron annihilation with atomic electrons, we extend these limits in the 200-300 MeV region by almost an order of magnitude, touching for the first time the dark matter relic density constrained parameter combinations. Our new results demonstrate the power of the resonant annihilation process in missing energy dark-matter searches, paving the road to future dedicated e+ beam efforts