Investigations for the use of the fast digitizers with C6D6 detectors for radiative capture measurements at GELINA
Investigations for the use of the fast digitizers with C6D6 detectors for radiative capture measurements at GELINA
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研究使用带有 C6D6 探测器的快速数字化仪在 GELINA 进行辐射捕获测量
DOI：
10.1016/j.nima.2008.11.119
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发表时间：
2009
影响因子：
1.4
通讯作者：
P. Schillebeeckx
中科院分区：
文献类型：
--
作者：
L. Mihailescu;A. Borella;C. Massimi;P. Schillebeeckx
在同时提供脉冲高度和所检测事件的时间信息的常规数据采集系统中的相对长的死区时间阻碍了具有高计数率的横截面测量。在飞行时间设施GELINA使用高放射性样品或具有强共振的厚材料样品进行俘获截面测量就是这种情况。高平均计数率（例如，由于样品的放射性）或用于强共振的高瞬时计数率导致大的死区时间校正。减少死区时间影响的一种解决方案是使用基于快速数字化仪的数据采集系统。本文测试了两种商用数字化仪（CAEN N172B和Acquiris DC 282）与C6D6闪烁体的脉冲高度线性度和分辨率、死区时间和时间分辨率。信号处理是在线完成的，同时获得每个检测到的事件的脉冲高度和时间信息。用这两种数字转换器，可以获得与传统系统相当的脉冲高度线性度和分辨率。两种数字系统的总死区时间至少比传统系统的死区时间短5倍。这两种数字化仪之间的主要性能差异是时间分辨率。对于较大的闪烁体，DC 282模块和常规系统的时间分辨率约为2ns，而CAEN N1728B模块的时间分辨率仅为15ns。对于大多数原子核，15ns的时间分辨率足以进行共振形状分析。因此，CAEN N1728B模块可用于GELINA的大多数捕获横截面测量。然而，对于具有低能级密度的核，其分辨共振区域延伸到keV区域，需要更好的时间分辨率，并且必须使用Acquiris DC 282模块。
The relatively long dead time in conventional data acquisition systems that provide simultaneously the pulse height and the time information for the detected events hinders cross-section measurements with high count rates. This is the case for capture cross-section measurements at the time-of-flight facility GELINA using high radioactive samples or thick samples of materials having strong resonances. Either the high average count rate (e.g. due to the radioactivity of the sample) or the high instantaneous count rate for strong resonances results in a large dead time correction. One solution to reduce the impact of the dead time is the use of a data acquisition system based on fast digitizers. The performances of two commercial digitizers (CAEN N172B and Acqiris DC282), coupled to a C6D6scintillator, have been tested in terms of pulse height linearity and resolution, dead time and time resolution. The signal processing was done on-line obtaining simultaneously the pulse height and time information for each detected event. With both digitizers a comparable pulse height linearity and resolution has been obtained as with a conventional system. The total dead time of both digital systems is at least a factor 5 shorter than the one for the conventional system. The main difference in performance between the two digitizers is the time resolution. For a relatively large scintillator, a time resolution of about 2ns has been achieved with the DC282 module and the conventional system while the time resolution was limited to 15ns with the CAEN N1728B module. For most nuclei a 15ns time resolution is sufficient to perform resonance shape analysis. Therefore, the CAEN N1728B module can be used for the majority of capture cross-section measurements at GELINA. However, for nuclei with low level density, for which the resolved resonance region extends to the keV-region, a better time resolution is required and the Acqiris DC282 module has to be used.