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Beam Test Characterization of Silicon Microstrip Detector Flight-Model Ladders for the AMS-02 Upgrade

Dexing Miao, Giovanni Ambrosi, Mattia Barbanera, Baasansuren Batsukh, Hengyi Cai, Mengke Cai, Xudong Cai, Yuman Cai, Yuan-Hann Chang, Shanzhen Chen, Hsin-Yi Chou, Xingzhu Cui, Mingyi Dong, Matteo Duranti, Ke Gong, Mingjie Feng, Valerio Formato, Yisheng Fu, Daojin Hong, Maria Ionica, Xiaojie Jiang, Yaozu Jiang, Liangchenglong Jin, Shengjie Jin, Vladimir Koutsenko, Qinze Li, Tiange Li, Zuhao Li, Chih-Hsun Lin, Changcheng Liu, Cong Liu, Hanbing Liu, Pingcheng Liu, Alberto Oliva, Ji Peng, Wenxi Peng, Rui Qiao, Shuqi Sheng, Tianyu Shi, Gianluigi Silvestre, Zetong Sun, Congcong Wang, Feng Wang, Hongbo Wang, Zhijie Wang, Zibing Wu, Zhiyu Xiang, Suyu Xiao, Weiwei Xu, Zixuan Yan, Haotian Yang, Sheng Yang, Yuhang You, Xuhao Yuan, Yuan Yuan, Fengze Zhang, Xiyuan Zhang, Zijun Xu, Jianchun Wang

Abstract

The AMS-02 experiment plans to install a new silicon microstrip tracker layer (Layer-0) on top of the existing detector, increasing the cosmic-ray acceptance by a factor of 3. Layer-0 employs a design in which multiple silicon microstrip detectors (SSDs) are connected in series to form long detector ladders. We present a detailed performance study of the flight-model ladders using a 350~GeV mixed hadron beam at the CERN SPS. The study focuses on the following aspects: (i) the performance of ladders with different numbers of SSDs, for which the intrinsic spatial resolution at normal incidence varies from $9.5~μ\mathrm{m}$ to $11.4~μ\mathrm{m}$ for ladders composed of 8 to 12 SSDs; (ii) the response consistency for particles impacting on the \emph{Head} and \emph{Tail} regions of the ladder; and (iii) the dependence of the detector performance on the particle incidence angle.

Beam Test Characterization of Silicon Microstrip Detector Flight-Model Ladders for the AMS-02 Upgrade

Abstract

The AMS-02 experiment plans to install a new silicon microstrip tracker layer (Layer-0) on top of the existing detector, increasing the cosmic-ray acceptance by a factor of 3. Layer-0 employs a design in which multiple silicon microstrip detectors (SSDs) are connected in series to form long detector ladders. We present a detailed performance study of the flight-model ladders using a 350~GeV mixed hadron beam at the CERN SPS. The study focuses on the following aspects: (i) the performance of ladders with different numbers of SSDs, for which the intrinsic spatial resolution at normal incidence varies from to for ladders composed of 8 to 12 SSDs; (ii) the response consistency for particles impacting on the \emph{Head} and \emph{Tail} regions of the ladder; and (iii) the dependence of the detector performance on the particle incidence angle.

Paper Structure

This paper contains 8 sections, 1 equation, 8 figures.

Table of Contents

  1. Introduction
  2. Design and configuration of AMS-02 Layer-0 ladders
  3. Test beam experiment
  4. Performance of the Layer-0 ladders
  5. Comparison of ladders with different numbers of SSDs
  6. Comparison of Head and Tail SSD
  7. Performance with the incidence angle
  8. Summary

Figures (8)

  • Figure 1: (a) Left: schematic view of the Layer-0 installed on the top of the AMS-02 detector. Right: side perspective view illustrating the relative size of Layer-0 with respect to the existing silicon tracker layers (L1--L9). (b) Schematic overview of the Layer-0 layout. The upper left panel shows a single detector ladder. The lower left panel presents the top view of the complete Layer-0 assembly, while the right panels display the top and bottom views. The Layer-0 consists of two planes, comprising a total of 72 ladders and 768 silicon microstrip sensors. The images are taken from Ref. Gargiulo2025AMS02.
  • Figure 2: A 12-SSD detector ladder of the AMS Layer-0 tracker. The front-end readout board is located on the left, while the 12 SSDs are connected in series via bonding wires on the right, as shown in the magnified view. The SSD closest to the front-end readout board is defined as the Head, the farthest one as the Tail, and the central SSD (the sixth one) as the Middle; these positions are indicated in the figure.
  • Figure 3: (a) Photograph of the beam test setup. Along the beam direction, the upstream beam monitor (BM1), the ladder under test, and the downstream beam monitor (BM2) are arranged sequentially. Open windows on the aluminum support box of the ladder to allow the beam to pass through. (b) Photograph showing the internal structure of a beam monitor.
  • Figure 4: (a) Intrinsic noise distributions of ladders with 8, 10, and 12 SSDs. The average noise values are 7.6, 8.7, and 9.7 LSB, respectively. (b) Cluster value distributions for the 8-, 10-, and 12-SSD ladders measured when the beam hits the Middle SSD, with the corresponding MPVs all around 75 LSB.
  • Figure 5: (a) (b) (c) Measured residual distributions for the 8-, 10-, and 12-SSD ladders, respectively. The $\sigma_{\mathrm{mea}}$ values, obtained from double-Gaussian fits, are indicated in each panel. (d) Intrinsic spatial resolution ($\sigma_{\mathrm{DUT}}$) as a function of the number of SSDs after subtracting the telescope contribution.
  • ...and 3 more figures