High-precision direct decay energy measurements of the electron-capture decay of $^{97}$Tc
Zhuang Ge, Tommi Eronen, Vasile Alin Sevestrean, Marlom Ramalho, Ovidiu Nitescu, Stefan Ghinescu, Sabin Stoica, Jouni Suhonen, Antoine de Roubin, Dmitrii Nester… 展开作者
Zhuang Ge, Tommi Eronen, Vasile Alin Sevestrean, Marlom Ramalho, Ovidiu Nitescu, Stefan Ghinescu, Sabin Stoica, Jouni Suhonen, Antoine de Roubin, Dmitrii Nesterenko, Anu Kankainen, Pauline Ascher, Samuel Ayet San Andres, Olga Beliuskina, Pierre Delahaye, Mathieu Flayol, Mathias Gerbaux, Stéphane Grévy, Marjut Hukkanen, Arthur Jaries, Ari Jokinen, Audric Husson, Daid Kahl, Joel Kostensalo, Jenni Kotila, Iain Moore, Stylianos Nikas, Jouni Ruotsalainen, Marek Stryjczyk, Ville Virtanen
利用双潘宁阱质谱仪JYFLTRAP的高分辨相位成像离子回旋共振技术，对$^{97}$Tc的基态到基态电子俘获衰变$Q$值（$Q_{\ m EC}$）进行了直接测量。所得$^{97}$Tc的$Q_{\ m EC}$值为324.82(21) keV，其精度比最新原子质量评估（AME2020）中采用的数值高约19倍，且相差1.2$σ$。此外，通过将该精化$Q$值与衰变子体$^{97}$Mo的核能级数据相结合，评估了一个可能的超低$Q$值跃迁，该跃迁可能属于容许型，即$^{97}$Tc（9/2$^{+}$，基态）$\ ightarrow$ $^{97}$Mo$^{*}$（320(1) keV），以用于未来的长期中微子质量测定实验。该跃迁的基态到激发态电子俘获衰变$Q$值（$Q^{*}_{\ m EC}$）被确定为4.8(10) keV，证实其在能量上是允许的，置信度超过4$σ$。对于该跃迁，占据L壳层及更高壳层的电子的俘获在能量上是允许的，给出$Q^{*}_{\ m EC}$与L1壳层允许结合能之间最近距离的值为2.0(10) keV。为了预测该跃迁的部分半衰期和能量释放分布，采用了原子自洽多电子Dirac–Hartree–Fock–Slater方法和核壳模型。交换修正和重叠修正等主要修正项，以及shake-up和shake-off效应，均被纳入最终结果。此外，将$^{97}$Tc电子俘获衰变至$^{97}$Mo激发态的归一化释放能量分布与正用于电子中微子质量测定的$^{163}$Ho的相应分布进行了比较。
英文摘要：
A direct measurement of the ground-state-to-ground-state electron-capture decay $Q$ ($Q_{\rm EC}$) value of $^{97}$Tc has been conducted employing the high resolving power phase-imaging ion-cyclotron-resonance technique with the double Penning trap mass spectrometer JYFLTRAP. The resulting $Q_{\rm EC}$ value for $^{97}$Tc is 324.82(21) keV, exhibiting a precision approximately 19 times higher than the value adopted in the newest Atomic Mass Evaluation (AME2020) and differing by 1.2$σ$. Furthermore, by combining this refined $Q$ value with nuclear energy-level data for the decay-daughter $^{97}$Mo, a potential ultra-low Q-value transition, possibly of allowed type, $^{97}$Tc (9/2$^{+}$, ground state) $\rightarrow$ $^{97}$Mo$^{*}$ (320(1) keV), was evaluated for future long-term neutrino-mass determination experiments. The ground-state-to-excited-state electron-capture decay $Q$ value ($Q^{*}_{\rm EC}$) of this transition was determined to be 4.8(10) keV, confirming it to be energetically allowed with a confidence level of exceeding 4$σ$. The captures of electrons occupying the L and higher shells for this transition are energetically allowed, giving a value of 2.0(10) keV for the closest distance of $Q^{*}_{\rm EC}$ to the allowed binding energy of the L1 shell. To predict partial half-lives and energy-release distributions for this transition, the atomic self-consistent many-electron Dirac--Hartree--Fock--Slater method and the nuclear shell model have been employed. Dominant correction terms such as exchange and overlap corrections, as well as shake-up and shake-off effects, were included in the final results. Moreover, the normalized distribution of released energy in the electron-capture decay of $^{97}$Tc to excited states of $^{97}$Mo, is compared with that of $^{163}$Ho, which is being used for electron-neutrino-mass determination.
A New Approach to Determine Radiative Capture Reaction Rates at Astrophysical Energies
辐射俘获反应在恒星核合成中起着至关重要的作用，但已被证明具有挑战性的实验确定。特别是，在任何恒星演化模型中，测量的$^{12}$ C $(α,γ)^{16}$ O反应速率的大不确定性（$\sim$ 100%）是最大的不确定性来源。随着新的高电流能量回收直线加速器（ERLs）和高密度气体靶的发展，使用细致平衡测量接近阈值的$^{16}$ O $(e,e^\prime α)^{12}$ C反应开辟了一种新的方法来确定$^{12}$ C $(α,γ)^{16}$ O反应速率，其精度显著提高（$<$ 20%）。我们提出的形式主义与光和电衰变反应，并考虑设计一个最佳的实验，以提供更高的精度。一旦新的ERLs上线，应该进行实验来验证我们提出的新方法。这种新方法对天体物理中的辐射俘获反应具有广泛的适用性。
Observation of an ultra-low $Q$-value electron-capture channel decaying to $^{75}$As via high-precision mass measurement
利用双潘宁阱质谱仪JYFLTRAP对$^{75}$ As的原子质量进行了精确测定。质量过量测量值为-73035.519（42）keV/c $^2$，比最新原子质量评估（AME 2020）中采用的值高21倍，低1.3（9）keV/c $^2$。该值已被用于确定$^{75}$ Se的基态到基态电子俘获衰变$Q$值和$^{75}$ Ge的$β^-$衰变$Q$值，它们分别被导出为866.041（81）keV和1178.561（65）keV。利用860.00（40）keV、865.40（50）keV的核能级数据（电子捕获的最终状态）和1172.00（60）keV（$β^-$衰变的最终状态）对于$^*$的激发态，我们已经确定了基态到激发态对于$^{75}$ Se $\rightarrow$ $^{75}$ As $^*$的两个转变和$^{75}$ Ge $\rightarrow$ $^{75}$ As $^*$的一个转变，状态$Q$值。基态到激发态$Q$的能量分别为6.04（41）keV、0.64（51）keV和6.56（60）keV，从而证实了三个低$Q$跃迁在能量上都是有效的，其中一个可能是确定反中微子质量的候选通道.此外，跃迁$^{75}$ Se $\rightarrow$ $^{75}$ As $^*$的基态到激发态的$Q$值（865.40（50）keV）被揭示为超低（< 1 keV）…
Probing the N=104 midshell region for the r process via precision mass spectrometry of neutron-rich rare-earth isotopes with the JYFLTRAP double Penning trap
