Observation of time-dependent internal charge amplification in a planar germanium detector at cryogenic temperature
Observation of time-dependent internal charge amplification in a planar germanium detector at cryogenic temperature
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DOI：
10.1140/epjc/s10052-023-11432-y
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发表时间：
2022-11
期刊：
影响因子：
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通讯作者：
P. Acharya;M. Fritts;Dongbin Mei;V. Mandic;C.-J. Wang;R. Mahapatra;M. Platt
中科院分区：
文献类型：
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作者：
P. Acharya;M. Fritts;Dongbin Mei;V. Mandic;C.-J. Wang;R. Mahapatra;M. Platt
首次在低温下工作的平面锗（Ge）探测器中观察到了碰撞电离产生的随时间变化的内部电荷放大。在施加偏置电压之后的30和45分钟的时间段内，对应于来自aAm源的59.54 keV射线的基线的电荷能量被放大一段短时间，然后减小回到基线。电荷能量的放大在很大程度上取决于所施加的正偏置电压，并且探测器上有漂移空穴。在探测器上漂移的电子不会出现这种现象。我们发现，所观察到的电荷放大是由带电态的碰撞电离决定的，它与杂质能级和外加电场有很强的相关性。我们分析了占主导地位的物理机制，负责创建和带电状态的碰撞电离。我们的分析表明，在Ge探测器中适当的杂质水平可以通过带电态的碰撞电离来提高电荷产额，以实现极低的能量探测阈值（< 10 meV），如果电荷放大可以稳定的MeV尺度的暗物质搜索。
For the first time, time-dependent internal charge amplification through impact ionization has been observed in a planar germanium (Ge) detector operated at cryogenic temperature. In a time period of 30 and 45 min after applying a bias voltage, the charge energy corresponding to a baseline of the 59.54 keVrays from aAm source is amplified for a short period of time and then decreases back to the baseline. The amplification of charge energy depends strongly on the applied positive bias voltage with drifting holes across the detector. No such phenomenon is visible with drifting electrons across the detector. We find that the observed charge amplification is dictated by the impact ionization of charged states, which has a strong correlation with impurity level and applied electric field. We analyze the dominant physics mechanisms that are responsible for the creation and the impact ionization of charged states. Our analysis suggests that the appropriate level of impurity in a Ge detector can enhance charge yield through the impact ionization of charged states to achieve extremely low-energy detection threshold (< 10 meV) for MeV-scale dark matter searches if the charge amplification can be stabilized.