Cell response equalisation of the ATLAS electromagnetic calorimeter without the direct knowledge of the ionisation signals
Cell response equalisation of the ATLAS electromagnetic calorimeter without the direct knowledge of the ionisation signals
复制标题
ATLAS 电磁量热仪的细胞响应均衡，无需直接了解电离信号
DOI：
10.1088/1748-0221/1/08/p08001
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发表时间：
2006
影响因子：
1.3
通讯作者：
M. Fanti
中科院分区：
文献类型：
--
作者：
D. Banfi;M. Delmastro;M. Fanti
ATLAS液体氩气电磁量热计提供频率为40 MHz的多次采样数字化信号。利用数字滤波技术从采样中重构信号幅度；数字滤波器权重的计算需要精确了解前端电子器件产生的信号的形状。每个读出通道都可以通过模拟电磁阵雨产生的电离信号的电子脉冲来校准。然而，校准信号与电离信号不同，因为注入的电流脉冲在形状（分别为指数/三角形）和注入点（在探测器端/探测器内部）上不同。为了执行正确的单元均衡，电离信号形状必须与用于计算每个通道实际电子增益的校准脉冲具有正确的归一化，从而考虑到上述差异。本文档描述了一组算法开发预测电离信号，仅从相应的校准脉冲中包含的信息。这种方法的优点是，每个通道的适当增益和每个细胞的电学性质的修正可以直接推断出来，然后嵌入到数字滤波重建中，而不需要直接了解细胞对阵雨诱导电离电流的响应。算法的性能已经在ATLAS液态氩气电磁量热计生产模块的电子束测试数据上进行了测试，证明了预测电离脉冲形状的能力与观测结果一致，优于1%（峰值为0.2%）。应用数字滤波权值重建245 GeV电子的能量，能量分辨率为0.8%，响应均匀性优于0.4%，满足ATLAS的性能要求。
The ATLAS liquid Argon electromagnetic calorimeter provides multiply-sampled digitised signals with a frequency of 40 MHz. The signal amplitude is reconstructed from the samples using a digital filtering technique; the computation of the digital filter weights requires the precise knowledge of the shape of the signal emerging from the front-end electronics. Each read-out channel can be calibrated by means of electronic pulsers that mimic the ionisation signal produced by an electromagnetic shower. However, the calibration signal differs from the ionisation one, because the injected current pulses are different in shape (exponential/triangular, respectively) and injection point (at the detector end/inside the detector). In order to perform a correct cell equalisation, the ionisation signal shape must have the correct normalisation with respect to the calibration pulse used to compute the actual electronic gain of each channel, thus taking into account the mentioned differences. This document describes a set of algorithms developed to predict the ionisation signal solely from the information contained in the corresponding calibration pulse. The advantage of this approach is that the proper gain of each channel and the corrections for the electrical properties of each cell can be directly inferred and then embedded in the digital filtering reconstruction, without any direct knowledge of the response of the cell to the shower-induced ionisation current. The performance of the algorithms has been tested on the electron test-beam data taken from an ATLAS liquid Argon electromagnetic calorimeter production module, demonstrating the ability to predict ionisation pulse shapes in agreement with the observed ones to better than 1% (0.2% at the peak). The digital filtering weights have been applied to reconstruct the energy of 245 GeV electrons with an energy resolution of 0.8% and a response uniformity better than 0.4%, which fulfill the ATLAS performance requirements.