Measurement of $\rm ^{6}H$ ground state energy in an electron scattering experiment at MAMI-A1
Tianhao Shao, Jinhui Chen, Josef Pochodzalla, Patrick Achenbach, Mirco Christmann, Michael O. Distler, Luca Doria, Anselm Esser, Julian Geratz, Christian Helmel… 展开作者
Tianhao Shao, Jinhui Chen, Josef Pochodzalla, Patrick Achenbach, Mirco Christmann, Michael O. Distler, Luca Doria, Anselm Esser, Julian Geratz, Christian Helmel, Matthias Hoek, Ryoko Kino, Pascal Klag, Yu-Gang Ma, David Markus, Harald Merkel, Miha Mihovilovič, Ulrich Müller, Sho Nagao, Satoshi N. Nakamura, Kotaro Nishi, Ken Nishida, Fumiya Oura, Jonas Pätschke, Björn Sören Schlimme, Concettina Sfienti, Daniel Steger, Marcell Steinen, Michaela Thiel, Andrzej Wilczek, Luca Wilhelm
For the first time the neutron-rich hydrogen isotope $\rm ^{6}H$ was produced in an electron scattering experiment in the reaction $\rm ^{7}Li(e,~e'pπ^{+})^{6}H$ using the spectrometer facility of the A1 Collaboration at the Mainz Microtron accelerator. By measuring the triple coincidence between the scattered electron, the produced proton, and $π^{+}$, the missing mass spectrum of $\rm ^{6}H$ was obtained. A clear peak above $^3$H+n+n+n energy threshold was seen resulting in a ground state energy of $\rm ^{6}H$ at $2.3\pm0.5({\rm stat.})\pm0.4({\rm syst.})$ MeV with a width of $1.9\pm1.0({\rm stat.})\pm0.4({\rm syst.})$ MeV. This work challenges the understandings of multi-nucleon interactions and presents a new method to study light neutron-rich nuclei with electron scattering experiments.
Beam-helicity asymmetry measurements in the Virtual Compton Scattering reaction in the g*N-Delta transition at Q2=0.20 (GeV/c)^2
本文报道了在Delta（1232）$ resonance at Q2=0.20 (GeV/c)2. The measurements were performed at MAMI and were carried out simultaneously with the measurement of the H(\vec{e},e'p)π^0 reaction channel. It is the lowest Q2 for which the $中H（\vec{e}，e 'p）γ反应的束流螺旋度不对称性的新测量。测量的不对称性进行了比较，并已被发现是很好地描述的色散关系（DR）计算的色散。本文用DR方法研究了数据对质子的广义极化率（GPs）和核子激发到Delta（1232）的振幅的敏感性。测量的不对称性已被发现表现出更高的灵敏度的GP，而它是建议，未来的测量更高的统计精度将提供更强的约束理论计算，并将提供有价值的洞察力对更完整的理解的GP的质子和π-N振幅。
Double polarization experiments at intermediate energy
在现代电子加速器与高度极化，强烈，高占空因数束双极化符合实验成为可行的良好的统计精度。通过MAMI最近的两个例子说明了精确测定小核子结构量的强大潜力。准自由反应$D(\vec e, e'\vec n)p$中$G_E^n$的测量导致$G_E^n$的新的参数化，其显著高于先前优选的弹性$e-D$散射。在$Δ$共振能量下的$p(\vec e, e'\vec p)π^0$实验产生了纵向四极混频的初步结果。实验误差和模型的不确定性都是对非偏振测量的补充。
Quasi-elastic scattering for the nuclear ground state structure: An intriguing case of $^{30}$Si
Bhabha Atomic Research Centre（巴巴原子研究中心）；Homi Bhabha National Institute（霍米·巴巴国立研究所）；Grand Accélérateur National d’Ions Lourds（大离子加速器）；CEA/DSM–CNRS/IN2P3（法国原子能和替代能源委员会/国家科学研究中心/核物理研究所联合实验室）；Amity University UP（阿米提北方邦大学）；Amity Institute of Nuclear Science & Technology（阿米提核科学与技术学院）；Department of Physics, IIT Roorkee（印度理工学院罗尔基分校物理系）；Kyoto University（京都大学）；SIES College of Arts, Science and Commerce（SIES文理商科学院）；Tata Institute of Fundamental Research（塔塔基础研究院）
A new measurement of the structure functions $P_{LL}-P_{TT}/epsilon$ and $P_{LT}$ in virtual Compton scattering at $Q^2=$ 0.33 (GeV/c)$^2$
在$Q^2 = 0.33$（GeV/c）$^2$处测量了$ep \to e' p' γ$反应的截面。该实验使用MAMI加速器的电子束和A1合作的标准检测器设置进行。用虚康普顿散射的低能定理分析了截面，得到了质子广义极化率线性组合的两个结构函数$P_LL}-P_{TT}/epsilon$和$P_{LT}$的新的确定.我们发现，在相同的$Q^2$的值比以前的调查稍大。然而，这种差异纯粹是由于我们对数据进行了更精细的分析。这些结果倾向于证实广义极化率的非平凡的$Q^2$演化，并呼吁在低$Q^2$区域（$\le$ 1（GeV/c）$^2$）进行更多的测量。
