First measurement of the polarization observable $E$ and helicity-dependent cross sections in single $π^{0}$ photoproduction from quasi-free nucleons
M. Dieterle, L. Witthauer, F. Cividini, S. Abt, P. Achenbach, P. Adlarson, F. Afzal, Z. Ahmed, C. S. Akondi, J. R. M. Annand, H. J. Arends, M. Bashkanov, R. Bec… 展开作者
M. Dieterle, L. Witthauer, F. Cividini, S. Abt, P. Achenbach, P. Adlarson, F. Afzal, Z. Ahmed, C. S. Akondi, J. R. M. Annand, H. J. Arends, M. Bashkanov, R. Beck, M. Biroth, N. S. Borisov, A. Braghieri, W. J. Briscoe, S. Costanza, C. Collicott, A. Denig, E. J. Downie, P. Drexler, M. I. Ferretti-Bondy, S. Gardner, S. Garni, D. I. Glazier, D. Glowa, W. Gradl, M. Günther, G. M. Gurevich, D. Hamilton, D. Hornidge, G. M. Huber, A. Käser, V. L. Kashevarov, S. Kay, I. Keshelashvili, R. Kondratiev, M. Korolija, B. Krusche, A. B. Lazarev, J. M. Linturi, V. Lisin, K. Livingston, S. Lutterer, I. J. D. MacGregor, J. Mancell, D. M. Manley, P. P. Martel, V. Metag, W. Meyer, R. Miskimen, E. Mornacchi, A. Mushkarenkov, A. B. Neganov, A. Neiser, M. Oberle, M. Ostrick, P. B. Otte, D. Paudyal, P. Pedroni, A. Polonski, S. N. Prakhov, A. Rajabi, G. Reicherz, G. Ron, T. Rostomyan, A. Sarty, C. Sfienti, M. H. Sikora, V. Sokhoyan, K. Spieker, O. Steffen, I. I. Strakovsky, Th. Strub, I. Supek, A. Thiel, M. Thiel, A. Thomas, M. Unverzagt, Yu. A. Usov, S. Wagner, N. K. Walford D. P. Watts, D. Werthmüller, J. Wettig, M. Wolfes, L. Zana
The double-polarization observable $E$ and the helicity-dependent cross sections $σ_{1/2}$ and $σ_{3/2}$ have been measured for the first time for single $π^{0}$ photoproduction from protons and neutrons bound in the deuteron at the electron accelerator facility MAMI in Mainz, Germany. The experiment used a circularly polarized photon beam and a longitudinally polarized deuterated butanol target. The reaction products, recoil nucleons and decay photons from the $π^0$ meson were detected with the Crystal Ball and TAPS electromagnetic calorimeters. Effects from nuclear Fermi motion were removed by a kinematic reconstruction of the $π^{0}N$ final state. A comparison to data measured with a free proton target showed that the absolute scale of the cross sections is significantly modified by nuclear final-state interaction (FSI) effects. However, there is no significant effect on the asymmetry $E$ since the $σ_{1/2}$ and $σ_{3/2}$ components appear to be influenced in a similar way. Thus, the best approximation of the two helicity-dependent cross sections for the free neutron is obtained by combining the asymmetry $E$ measured with quasi-free neutrons and the unpolarized cross section corrected for FSI effects under the assumption that the FSI effects are similar for neutrons and protons.
Helicity-Dependent Angular Distributions for Double-Charged-Pion Photoproduction
在Jefferson实验室Hall B使用能量范围在0.6 GeV和2.3 GeV之间的圆偏振标记光子束研究了γ p -> p pi+ pi-反应中的2 π介子光生。测量了末态粒子的角分布与束流螺旋度的关系。大横截面的不对称性，已被发现表现出强烈的敏感性的反应的运动学，并与初步模型计算Mokeev和罗伯茨。
Helicity-Dependent Angular Distributions in Double-Charged-Pion Photoproduction
在杰斐逊实验室大厅B，使用能量范围在0.6 GeV和2.3 GeV之间的圆偏振标记光子束，研究了伽马+ p -> p + pi^+ + pi^-反应中的双π介子光生。由于CLAS探测器的大角度接受能力，测量了末态粒子的完全束螺旋度相关的角分布。大截面的不对称性表现出强烈的灵敏度的反应的运动学，并提供有价值的信息的反应动力学。初步结果。
Accessing transverse nucleon and gluon distributions in heavy nuclei using coherent vector meson photoproduction at high energies in ion ultraperipheral collisions
