~（173）Hg原子激发态的首次观测

$^{12}$ C第一激发态Hoyle衰变的直接观测

Direct observation of the decay of first excited Hoyle state in $^{12}$C

$^{12}$ C的激发态具有激发能$_x \sim$ 9.65 $\pm$ 0.02 MeV和宽度（FWHM）$\sim607\pm$ 55 keV，其通过Hoyle态衰变为三个$ α$ -粒子（$E_x \sim$ 7.65 MeV），首次在60 MeV $^{4}$ He在$^{12}$ C上的非弹性散射中被直接识别，通过对完全检测到的（4个$ α$）事件进行逐事件运动学重建，与反冲$^{12}$ C $ ^* $ Hoyle状态（主要以$^{12}$ C $ ^* $ $\rightarrow \ ^{8} $ Be + $ α$ $\rightarrow \ α+ α+ α$形式衰减）一致地测量。这种状态很可能是2 $_2^+$第一激发霍伊尔态的候选者，其存在最近已被间接证明从最近的包容性非弹性散射研究。

115-In到115-Sn第一激发能级的β衰变：中微子质量的可能结果

Beta decay of 115-In to the first excited level of 115-Sn: Potential outcome for neutrino mass

最近对115-In到115-Sn第一激发能级的β衰变的观测表明，Q_β值很低（Q_β ~ 1 keV），这可能是中微子质量的一个限制。为了给出与从3-H（~2 eV）和187-Re（~15 eV）实验中提取的限制潜在竞争的限制，115-In和115-Sn之间的原子质量差和第一个115-Sn能级的能量应该以更高的精度（可能在~1 eV的量级）重新测量。

Observation of the $^7$H excited state

The $^7$H system was populated in the $^2$H($^8$He,$^3$He)$^7$H reaction with a 26 AMeV $^8$He beam. The $^{7}$H missing mass energy spectrum, the $^{3}$H energy and angular distributions in the $^7$H decay frame were reconstructed. The $^7$H missing mass spectrum shows a peak which can be interpreted either as unresolved $5/2^+$ and $3/2^+$ doublet or one of these states at 6.5(5) MeV. The data also provide indications on the $1/2^+$ ground state of $^7$H located at 2.0(5) MeV with quite a low population cross section of $\sim 10$ $μ$b/sr within angular range $θ_{\text{cm}} \simeq 6^{\circ} -…

First search for $2\varepsilon$ and $\varepsilonβ^+$ decay of $^{162}$Er and new limit on $2β^{-}$ decay of $^{170}$Er to the first excited level of $^{170}$Yb

The first search for double electron capture ($2\varepsilon$) and electron capture with positron emission ($\varepsilonβ^+$) of $^{162}$Er to the ground state and to several excited levels of $^{162}$Dy was realized with 326 g of highly purified erbium oxide. The sample was measured over 1934 h by the ultra-low background HP Ge $γ$ spectrometer GeCris (465 cm$^3$) at the Gran Sasso underground laboratory. No effect was observed, the half-life limits were estimated at the level of $\lim T_{1/2}\sim 10^{15}-10^{18}$ yr. A possible resonant $0νKL_1$ capture in $^{162}$Er to the $2^+$ 1782.7 keV e…

Observation of excited states in $^{20}$Mg sheds light on nuclear forces and shell evolution

The exotic Borromean nucleus $^{20}$Mg with $N$ = 8, located at the proton drip-line provides a unique testing ground for nuclear forces and the evolution of shell structure in the neutron-deficient region. We report on the first observation of proton unbound resonances together with bound states in $^{20}$Mg from the $^{20}$Mg($d$,$d'$) reaction performed at TRIUMF. Phenomenological shell-model calculations offer a reasonable description. However, our experimental results present a challenge for current first-principles nuclear structure approaches and point to the need for improved chiral fo…

Pd110和Pd102双β衰变到激发态的新Half-life极限

New Half-life Limits on Double Beta Decays of Pd110 and Pd102 into Excited States

在HADES地下实验室用两个低本底HPGe探测器夹心结构，对Pd_（110）双β衰变和Pd_（102）双电子俘获的激发态跃迁进行了研究。经35.92 kg·d暴露后，未发现信号，经频谱分析，Pd_（110）第一个0+和2+激发态的半衰期下限分别为1.98 e20年和1.72 e20年（95%CL）。相对于先前的测量，这是超过3倍的改进。在Pd 102中，第一个0+激发态的半衰期下限可提高到5.95 e18年（95%CL）。此外，第一个实验的半衰期下限被发现的所有可能的激发态在Pd 110和Pd 102系统。

Pd110和Pd102激发态双β和双电子俘获衰变的初步研究

A first search of excited states double beta and double electron capture decays of Pd110 and Pd102

对钯同位素110 Pd和102 Pd衰变到其子体激发态的双β衰变进行了研究，得到了110 Pd衰变到第一激发态0+和2+的第一半衰期极限分别为5.89 e 19 yr和4.40 e 19 yr（95%CL）。相应的102 Pd双电子俘获跃迁的半衰期极限分别为7.64e ~（18）yr和2.68e ~（18）yr（95%CL）。这是对102 Pd的首次测量。

Two-neutrino $ββ$ decay of $^{136}$Xe to the first excited $0^+$ state in $^{136}$Ba

We calculate the nuclear matrix element for the two-neutrino $ββ$ decay of $^{136}$Xe into the first excited $0^+$ state of $^{136}$Ba. We use different many-body methods: the quasiparticle random-phase approximation (QRPA) framework, the nuclear shell model, the interacting boson model (IBM-2), and an effective field theory (EFT) for $β$ and $ββ$ decays. While the QRPA suggests a decay rate at the edge of current experimental limits, the shell model points to a half-life about two orders of magnitude longer. The predictions of the IBM-2 and the EFT lie in between, and the latter provides syst…

手征夸克模型中高激发态重轻介子的强衰变

Strong decays of higher excited heavy-light mesons in a chiral quark model

在组分夸克模型中研究了高激发态重轻介子从第一径向激发态到第一$F$波态的强衰变性质。研究发现，许多失激发态的宽度很窄，在未来的实验中有很好的发现潜力，其中一些失激发态主要衰变到第一轨道激发态而不是基态。在未来的观测中，人们不仅应该关注到基态的衰变过程，而且还应该关注到$J^P=0^+,1^+$的低位$P$波激发。此外，还讨论了新观测到的态$D_J(3000)$，$D_J^*(3000)$和B（5970）的性质.预测$D_J(3000)$可能是$D_{sJ}(3040)$的伙伴，通过$2^1P_1$ - $2^3P_1$混合，可确定为高质量混合态$|2{P_1}>_L$（$J^P=1^+$）。$D_J^*(3000)$共振似乎更倾向于$1^3F_4$态，但量子数$J^P=0^+$和$2^+$不能完全排除，其$J^P$值还需要更多的实验观测来确定。B（5970）共振最有可能是$1^3D_3$与$J^P=3^-$。