Electron scattering from light deformed nuclei
Electron scattering from light deformed nuclei
Braley, R. C.↗
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Observation of Azimuth-Dependent Suppression of Hadron Pairs in Electron Scattering off Nuclei
Here, we present the first measurement of dihadron angular correlations in electron-nucleus scattering. The data were taken with the CLAS detector and a 5.0 GeV electron beam incident on deuterium, carbon, iron, and lead targets. Relative to deuterium, the nuclear yields of charged-pion pairs show a strong suppression for azimuthally opposite pairs, no suppression for azimuthally nearby pairs, and an enhancement of pairs with large invariant mass. These effects grow with increased nuclear size. The data are qualitatively described by the GIBUU model, which suggests that hadrons form near the nuclear surface and undergo multiple scattering in nuclei. These results show that angular correlation studies can open a new way to elucidate how hadrons form and interact inside nuclei.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Electron scattering from light deformed nuclei
High energy electrons elastic scattering from 2s-1d shell nuclei based on Dirac equation solution in Glauber approximation
Braley, R. C.↗
Electron and neutrino scattering from nuclei [Slides]
The knowledge of how electrons and neutrinos interact in nuclei is fundamental for many reasons, and the proper inclusion of many-body correlations between nucleons is crucial. The calculation of the nuclei from two- and three-nucleon interactions obtained from first principle is, however, one of the most challenging problems for many-body nuclear physics.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
Elastic Electron Scattering From Mirror Nuclei 3He and 3H
The primary aim of my work is the extraction of the elastic cross-sections from data collected in Jefferson Lab Hall A experiment E12-11-112 which measured inclusive elastic scattering from the mirror nuclei 3He and 3H at low momentum transfer Q2 ? 0.1 GeV2. The obtained 3H cross-section is 0.630 ± 0.027 ?barn/sr with fractional uncertainty 4.35% and 3He cross- section is 1.274 ± 0.055 ?barn/sr with fractional uncertainty 4.29% . I determined the ratio of the 3He and 3H cross-sections since it cancels many of the systematic uncertainties that enter into the absolute cross-section extraction, and it reduced the fractional uncertainty to 1.85%.
Kurbany, Leiqaa↗
Development of fixed-nuclei approximations of electron-molecule scattering and the adiabatic theory of rotational excitation
Fixed nuclei approximations of electron-molecule scattering and adiabatic theory of rotational excitation
Temkin, A.↗
Electron scattering on A = 3 nuclei from quantum Monte Carlo based approaches
We perform first-principle calculations of electron-nucleus scattering on 3 He and 3 H using the Green's function Monte Carlo method and two approaches based on the factorization of the final hadronic state: the spectral-function formalism and the short-time approximation. These three methods are benchmarked among each other and compared to the experimental data for the longitudinal and transverse electromagnetic response functions of 3 He, and the inclusive cross sections of both 3 He and 3 H. Since these three approaches are based on the same description of nuclear dynamics of the initial target state, comparing their results enables a precise quantification of the uncertainties inherent to factorization schemes. At sufficiently large values of the momentum transfer, we find an excellent agreement of the Green's function Monte Carlo calculation with experimental data and with both the spectral-function formalism and the short-time approximation. Here, we also analyze the relevance of relativistic effects, whose inclusion becomes crucial to explain data at high momentum and energy transfer.
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
MEASUREMENT OF Fn 2 /Fp 2 FROM DEEP INELASTIC ELECTRON SCATTERING OFF A=3 MIRROR NUCLEI AT JEFFERSON LAB
This research is part of the Je?erson Lab MARATHON experiment (MeAsurement of the Fn 2 /Fp 2 , d/u RAtios and A = 3 EMC E?ect in Deep Inelastic Electron Scattering Off the Tritium and Helium MirrOr Nuclei). MARATHON is an experiment on electron deep inelastic scattering off the 3H, 3He mirror nuclei. It has extracted, from the measured deep inelastic scattering cross section ratio o? 3H and 3He, the ratio of the neutron to proton inelastic structure functions Fn 2 /Fp 2 . The extraction has taken advantage of the isospin symmetry of the A = 3 mirror nuclei within a novel technique, which avoids the theoretical uncertainties that are present in the SLAC experiments of the 1970s, which used hydrogen and deuterium targets. The experiment was performed using the upgraded 11 GeV beam of the Jefferson Lab electron accelerator, the Hall A Experimental Facility, and a newly designed cryogenic, high-pressure gas target system containing 3H and 3He cells. Electrons scattered o? the gas targets were detected in the two superconducting, high-resolution magnetic spectrometers of Hall A. The cross section data cover the four-momentum transfer squared range 2.0 < Q2 < 14.0 (GeV/c)2, and the Bjorken x scaling variable range 0.19 < x < 0.83. The experiment also measured, for calibration purposes, electron deep inelastic scattering off hydrogen and deuterium at selected kinematics.
Su, Tong↗
Electron scattering on ${\mathbf{A=3}}$ nuclei from quantum Monte Carlo based approaches
We perform first-principle calculations of electron-nucleus scattering on $^3$He and $^3$H using the Green's function Monte Carlo method and two approaches based on the factorization of the final hadronic state: the spectral-function formalism and the short-time approximation. These three methods are benchmarked among each other and compared to the experimental data for the longitudinal and transverse electromagnetic response functions of $^3$He, and the inclusive cross sections of both $^3$He and $^3$H. Since these three approaches are based on the same description of nuclear dynamics of the initial target state, comparing their results enables a precise quantification of the uncertainties inherent to factorization schemes. At sufficiently large values of the momentum transfer, we find an excellent agreement of the Green's function Monte Carlo calculation with experimental data and with both the spectral-function formalism and the short-time approximation. We also analyze the relevance of relativistic effects, whose inclusion becomes crucial to explain data at high momentum and energy transfer.
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
Study of light nuclei by polarization observables in electron scattering
Electron-induced proton, neutron and deuteron knock-out remains the most versatile probe of the electro-magnetic properties and spin structure of light nuclei. The advent of highly polarized beams and targets and improvements in recoil polarization methods, as well as analysis and simulation techniques, have enabled us to study the static and dynamical properties of few-body systems with unprecedented precision. Recent experiments at Jefferson Lab and MAMI are presented and put into perspective of state-of-the art Faddeev calculations, with focus on the ^\mathbf{3}\mathbf{He} 3 𝐇 𝐞 nucleus.
Sirca, Simon↗
Measurements of the Beam Normal Asymmetry using Polarized Elastic Electron Scattering off Various Spin-0 Nuclei at 1 GeV
In this first part of this thesis, I report on the 1 GeV beam normal asymmetry measurements (AT) on various spin-0 nuclei during PREX-II. In a QED framework, this P-even, T-odd observable is a direct probe of the imaginary part of the two-photon exchange amplitude, since time reversal symmetry dictates AT must vanish in the one-photon approximation. At ultrarelativistic energies, the beam normal asymmetry is sensitive to the hadronic structure of the target nucleus. Calculations of the two-photon exchange amplitude are challenging since one has to consider all intermediate hadronic states in the calculation. The treatment of the states are both model and kinematics dependent. Therefore direct measurements of the beam normal asymmetry can test theory models. For experiments which measure the parity-violating asymmetry APV,the beam normal asymmetry can enter as a false asymmetry for APV when the beam is not 100% longitudinally polarized.
Richards, Ryan↗
Short Range Correlations and Few Body Precision Measurements
This talk will discuss the exciting experimental program studying short range correlations and few body dynamics at Jefferson Lab in ?=3 nuclei. Quasi-elastic electron scattering on these light nuclei have readily calculable ground states but can already exhibit complex nuclear behavior including nucleon-nucleon (NN) short range correlations (SRCs). 3H and 3He, being mirror nuclei, exploit the maximum available isospin asymmetry and can be compared directly with ab initio calculations. This talk will summarize the recent Hall A 3H and 3He results. The first measurement of SRC nucleons in 3He using the CLAS detector from Hall B and identifying lead neutrons in ?? pairs at high missing momentum will be shown. These fascinating results will be extended in an approved experiment using the CLAS12 detector to measure high-statistics and absolute cross sections on 2H, 3He, and 3H with a wide range of kinematical coverage. This talk will discuss the recent and proposed measurements and their implications on nuclear models for few body nuclear dynamics and short range structure.
Szumila-Vance, Holly↗
Precise measurement of the nuclear dependence of the EMC effect in light nuclei
Measurements of inclusive electron scattering cross-section ratios from light nuclei over a wide range of the Björken G (0.3 ? G ? 1) up to &2 = 8.3 GeV2 were made as part of experiment E10-10-008, which was conducted in Hall C at the Thomas Jefferson National Accelerator Facility. The measurements were performed using a beam energy of 10.602 GeV and an average beam current of 45 `A. This dissertation provides a thorough description of the experiment as well as the extracted ratios of inclusive nuclear cross-sections with respect to the deuterium cross-sections (the EMC effect) for the targets 9Be, 12C, 10B, and 11B. The nuclear dependence of the inclusive inelastic electron scattering cross-section has been measured for the first time in 10B and 11B.
Karki, Abishek↗
Competing ionization and dissociation: Extension of the energy-dependent frame transformation to the gerade symmetry of H 2
This article solves two major tasks that frequently arise in the theory of electron collisions with a target molecular cation. First, it extends the energy-dependent frame transformation (EDFT) treatment, which is needed to map fixed-nuclei electron-molecule scattering matrices into an energy-dependent laboratory-frame scattering matrix with vibrational channel indices. The EDFT mapping can now be carried out even when the target molecule possesses multiple low-energy potential curves, significantly transcending previous applications. Second, it implements a method to extract the rest of the full laboratory-frame scattering matrix, i.e., the columns and rows describing input and/or output dissociation channels. The treatment is benchmarked in this article against the essentially exact solution of a refined two-dimensional model of the singlet gerade Σ symmetry of H 2 . Our tests demonstrate that the theory accurately maps fixed-nuclei scattering information, of the type provided by existing electron-molecule computer codes, into a laboratory-frame scattering matrix that includes both ionization and dissociation. Furthermore, this treatment can provide a general framework applicable to a broad class of electron collision processes involving diatomic target ions, suitable for an accurate description of challenging processes such as dissociative recombination.
74 ATOMIC AND MOLECULAR PHYSICS↗
Precision Møller polarimetry for PREX-2 and CREX
The PREX-2 and CREX experiments in Hall A at Jefferson Lab are precision measurements of parity violating elastic electron scattering from complex nuclei. One requirement was that the incident electron beam polarization, typically , be known with 1% precision. We commissioned and operated a Møller polarimeter on the beam line that exceeds this requirement, achieving a precision of 0.89% for PREX-2, and 0.85% for CREX. The uncertainty is purely systematic, accumulated from several different sources, but dominated by our knowledge of the target polarization. Our analysis also demonstrates the need for accurate atomic wave functions in order to correct for the Levchuk Effect. We describe the details of the polarimeter operation and analysis, as well as (for CREX) a comparison to results from a different polarimeter based on Compton scattering.
43 PARTICLE ACCELERATORS↗
New Measurements of the Beam-Normal Single Spin Asymmetry in Elastic Electron Scattering Over a Range of Spin-0 Nuclei
We report precision determinations of the beam-normal single spin asymmetries (A n ) in the elastic scattering of 0.95 and 2.18 GeV electrons off 12 C, 40 Ca, 48 Ca, and 208 Pb at very forward angles where the most detailed theoretical calculations have been performed. The first measurements of A n for 40 Ca and 48 Ca are found to be similar to that of 12 C, consistent with expectations and thus demonstrating the validity of theoretical calculations for nuclei with Z ≤ 20. We also report A n for 208 Pb at two new momentum transfers (Q 2 ) extending the previous measurement. Our new data confirm the surprising result previously reported, with all three data points showing significant disagreement with the results from the Z ≤ 20 nuclei. These data confirm our basic understanding of the underlying dynamics that govern A n for nuclei containing ≲ 50 nucleons, but point to the need for further investigation to understand the unusual A n behavior discovered for scattering off 208 Pb.
73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
Neutron Skin Measurement of208Pb Using Parity-Violating Electron Scattering
Nuclear stability requires large nuclei to have more neutrons than protons. While the central core of the nucleus is composed of symmetric nuclear matter, the extra neutrons in heavy nuclei are pushed out to the surface of the nucleus, forming a pure outer neutron skin layer. While the proton distribution inside a nucleus has been accurately measured using electromagnetic probes, previous measurements of neutron distributions in complex nuclei have suffered a lack of systematic precision. PREX-2 and CREX use Parity-Violating electron Scattering (PVeS), as an electroweak interaction probe, to measure the neutron distributions in208Pb and48Ca, respectively. Making use of elastic scattering of longitudinally polarized electrons from unpolarized (isotopically pure) targets, PREX-2 and CREX measure the asymmetry in scattering rates between opposite beam polarization states. Since both experiments share the same exact measurement concept and apparatus, much of this dissertation applies to both PREX-2 and CREX. However, the presented asymmetry analysis and neutron skin extraction are only for PREX-2. PREX-2 measures the parity-violating asymmetry, APV, for 953 MeV electrons scattered elastically from208Pb at?5°in the lab. The final result is APV= 550.00±16.09(stat.)±8.16(syst.)ppb. From this measurement, we report the neutron skin thickness in208Pb nuclei to be, Rskin= 0.278±0.078(exp.)±0.012(model) fm. This measurement has broad implications throughout the physics community, increasing our knowledge in neutron star structure, the equation of state of nuclear matter, nuclear baryon density, nuclear electric dipole polarizability, and more. Key Words: Neutron skin, electroweak interaction, PREX-2, CREX, parity-violating asymmetry, neutron star, quartz detector, weak charge radius, symmetry energy, Hall A, Jefferson Lab
Adhikari, Devi↗
Measurement of Parity Violating Asymmetry in Elastic Electron Scattering off 48Ca
Atomic nuclei are composed of nucleons governed by the strong nuclear force. Although the proton distributions in nuclei are well measured with electromagnetic probes, the neutron distributions are relatively unconstrained. The nuclear symmetry energy governs the distribution of the excess neutrons in asymmetric nuclei, as well as the dynamics of neutron-rich nuclear matter up to the scale of neutron stars….
Clarke, Cameron↗