We propose to measure the high-energy behavior of the integrand of the Gerasimov-Drell-Hearn (GDH) sum rule on the proton and the neutron up to 12 GeV. The convergence of the GDH integral will be investigated for the first time and to high precision. The validity of the GDH sum rule on the neutron will be accurately tested for the first time, while for the proton the uncertainty will be improved by $25\%$ relative. The data will allow precision testing of Regge phenomenology in the polarized domain. The $a_1$ and $f_1$ Regge trajectory intercepts will be obtained to an order of magnitude higher precision than the current best estimates. The data will also contribute to the determination of the real and imaginary parts of the spin-dependent Compton amplitude, the polarizability correction to hyperfine splitting in hydrogen, and to studying the transition between polarized DIS and diffractive regimes.
The experiment will require a circularly polarized photon beam (produced from a longitudinally polarized electron beam) with a flux approximately 1/3 of the GlueX-II experiment E12-13-003. The experiment will run in two configurations which require two different CEBAF beam energies. A new longitudinal polarized proton and deuteron target will be needed in Hall D. The experiment will require 21 PAC days at the nominal CEBAF energy and another 12 PAC days at an energy 1/3 to 1/2 of the nominal.
First Measurement of the Asymmetry and the Gerasimov-Drell-Hearn Integrand from $\vec{{^3}He}(\vecγ,p)d$ reaction at the Incident Photon Energy of 29 MeV
$\vec{^3He}(\vecγ,p)d$过程的第一次测量是在三角大学核实验室（TUNL）的高强度$γ$射线源（HI $γ$ S）设施中使用圆偏振的单能$γ$射线束和纵向偏振的$^3$ He靶进行的.在入射光子能量为29.0 MeV时，提取了自旋相关的不对称性和二体光蜕变对$^3$ He Gerasimov-Drell-Hearn被积函数的贡献，并与最新的三核子系统计算结果进行了比较.这些数据与基于Siegert定理或明确包含介子交换电流的各种理论预测基本一致。
Measurement of the Gerasimov-Drell-Hearn integrand for proton and deuteron from 200 to 1400 MeV
INFN Sezione di Pavia（意大利国家核物理研究所帕维亚分部）；Helmholtz-Institut für Strahlen- und Kernphysik, Universität Bonn（波恩大学亥姆霍兹辐射与核物理研究所）；Department für Physik, Universität Basel（巴塞尔大学物理系）；Institut für Kernphysik, University of Mainz（美因茨大学核物理研究所）；SUPA School of Physics and Astronomy, University of Glasgow（格拉斯哥大学SUPA物理与天文学学院）；Kitzbühel Centre for Physics（基茨比厄尔物理中心）；Marian Smoluchowski Institute of Physics, Jagiellonian University（亚盖隆大学马里安·斯莫卢霍夫斯基物理研究所）；Joint Institute for Nuclear Research（俄罗斯联合核研究所）；The George Washington University（乔治华盛顿大学）
